Dry composition for use in haemostasis and wound healing

ABSTRACT

The present disclosure relates to a dry composition which reconstitutes without mechanical mixing to form a flowable paste having a soft and light consistency suitable for use in haemostasis and wound healing procedures upon addition of an aqueous medium. The disclosure further relates to methods of preparing the dry composition, methods for reconstituting the dry composition and medical use of the composition.

TECHNICAL FIELD

The present disclosure relates to a method for preparing a drycomposition suitable for use in haemostasis and wound healingprocedures. The dry composition reconstitutes efficiently to form apaste having a soft, light consistency upon addition of an aqueousmedium without mechanically mixing air into the paste.

BACKGROUND

Protein-based haemostatic materials such as collagen and gelatine arecommercially available in solid sponge and loose or unpacked powder formfor use in surgical procedures. Mixing of the loose or unpacked powderwith a fluid such as saline or a thrombin solution may form a paste orslurry that is useful as a haemostatic composition for use in cases ofdiffuse bleeding, particularly from uneven surfaces or hard to reachareas, depending on mixing conditions and relative ratios of thematerials.

Conventional haemostatic pastes are usually prepared at the point of useby mechanical agitation and mixing of a biocompatible polymer, e.g.gelatine, and a liquid, e.g. a thrombin solution, to provide uniformityof the composition. Mixing to form a paste usually requires extensivemixing, such as kneading or transfer between two syringes.

WO 03/055531 relates to a container comprising a fixed amount ofhaemostatic agent in powder form, such as gelatine powder. Upon additionof a suitable amount of liquid, mechanical mixing within the containermay be performed by closing the lid and shaking the container. Theresultant putty-like haemostatic paste can then be removed from thecontainer and applied to a patient to promote haemostasis.

Surgiflo® Haemostatic Matrix (Ethicon) is a kit for producing ahaemostatic gelatine paste comprising thrombin, which is prepared bytransferring a gelatin matrix-thrombin solution mixture back and forthbetween two connected syringes for a total of at least six passes.Floseal® Haemostatic Matrix (Baxter) is likewise a kit for producing ahaemostatic gelatine paste, but requires transfer of the gelatinmatrix-thrombin solution mixture back and forth between two connectedsyringes for a total of at least twenty passes. Once a substantiallyhomogenous paste composition is achieved, the haemostatic pastes can beapplied to a bleeding to promote haemostasis by extruding the pastesfrom the syringe.

US 2005/0284809 relates to a method for preparing a haemostatic pastethat more readily absorbs aqueous liquids, such that less mechanicalforce and time is required in order to form a flowable haemostaticpaste. The paste of US 2005/0284809 is prepared from compressedhaemostatic powder particles and to prepare the paste, it must betransferred back and forth between connected syringes for a total of atleast five passes.

WO 2011/151400 relates to a process for making a dry haemostaticcomposition comprising a coagulation inducing agent such as thrombin anda biocompatible polymer such as gelatine. The coagulation inducing agentand the biocompatible polymer are mixed to form a paste and the paste issubjected to lyophilisation. The resulting dry composition isreconstituted by transferring the composition and a diluent back andforth between two connected syringes for a total of at least twentypasses as described previously.

Transfer between connected syringes ensures sufficient mixing of theliquid component and the gelatin matrix component. During the passes airis mixed into the paste, which affects the consistency of thereconstituted paste. However, mixing procedures and manipulations aretime consuming which in an Operation Room (OR) setting with bleedings isnot acceptable as the surgeon will have to abrupt his procedure whilewaiting for the haemostat. Mixing may also potentially compromise thesterility of the haemostatic paste and can in some cases even negativelyaffect the consistency of the haemostatic paste. Paste consistency is animportant parameter both for application of the paste and for adhesionof the paste to the wound.

WO 2013/185776 discloses a dry paste composition suitable for woundhealing and haemostatic use which reconstitutes spontaneously to form aflowable paste, i.e. without any mixing required, upon addition of anaqueous medium. The dry composition is prepared by mixing a crosslinkedbiocompatible polymer, one or more polyols and an aqueous medium toprepare a paste and then lyophilising the paste to obtain the drycomposition.

WO 2014/202760 discloses a dry composition suitable for wound healingand haemostatic use which reconstitutes spontaneously to form a flowablepaste, i.e. without any mixing needed, upon addition of an aqueousmedium. The dry composition is prepared by mixing a crosslinkedbiocompatible polymer and an aqueous medium to prepare a paste,expanding the paste by subjecting the paste to a reduced pressure,freezing the expanded paste and then drying the expanded, frozen pasteto obtain the dry composition.

As mentioned above, paste consistency can be important for thehaemostatic effect and adhesion of the paste to the tissue. In addition,the consistency of the reconstituted pastes can also be an importantparameter determining which types of surgeries the pastes are mostsuitable for. For instance, a softer paste consistency may be preferablein certain types of surgeries. Surgeon preferences also vary withregards to the consistency of the pastes, where some surgeons prefer asofter consistency than others. Thus, there is a need in the art fordeveloping dry paste compositions, wherein the consistency of thereconstituted paste can be more easily controlled.

SUMMARY OF INVENTION

The present disclosure addresses the above problems and thus provides adry composition, which upon addition of an aqueous medium forms asubstantially homogenous paste without any mechanical mixing required. Asoft and light consistency of the reconstituted paste is controlled bythe presence of an alkaline and an acidic compound, which are capable ofreacting to produce a gas upon wetting of the dry composition. The gasproduced upon reaction of the acid and the base expands inside thecomposition being reconstituted and results in a paste having adesirable soft and light consistency without having to introduce air bymechanical mixing procedures.

The release of a gas upon wetting of the dry composition can be achievedin at least three alternative ways:

-   -   1. By preparing a dry composition comprising an alkaline        compound and reconstituting with a liquid comprising an acidic        compound.    -   2. By preparing a dry composition comprising an acidic compound        and reconstituting with a liquid comprising an alkaline        compound.    -   3. By preparing a dry composition comprising both an alkaline        compound and an acidic compound and reconstituting with an        aqueous medium, for instance water.

The alkaline compound and the acidic compound are capable of reacting inthe presence of an aqueous medium to release a gas.

Thus, in a first embodiment, the invention relates to a method forpreparing a dry composition comprising the steps of:

-   -   a) mixing a biocompatible polymer in powder form, an aqueous        medium and an alkaline compound to obtain a paste, and    -   b) drying the paste,    -   wherein the alkaline compound is capable of reacting with an        acidic compound in an aqueous medium to release a gas.

In a second embodiment, the invention relates to a method for preparinga dry composition comprising the steps of:

-   -   a) mixing a biocompatible polymer in powder form, an aqueous        medium and an acidic compound to obtain a paste, and    -   b) drying the paste,    -   wherein the acidic compound is capable of reacting with an        alkaline compound in an aqueous medium to release a gas.

In a third embodiment, a dry composition comprising either an alkalineor an acidic compound is further added:

-   -   a) an acidic compound in dry form after the paste has been dried        if the dry composition already comprises an alkaline compound,        or    -   b) an alkaline compound in dry form after the paste has been        dried if the dry composition already comprises and acidic        compound.    -   wherein the acidic compound and the alkaline compound are        capable of reacting in the presence of an aqueous medium to        release a gas.

The dry composition prepared by the above methods reconstitutesefficiently upon addition of a suitable liquid to a paste having a softand “fluffy” consistency. The paste forms independently of externalstimuli, such as mixing or stirring of any kind.

The present disclosure further relates to a dry composition obtainableby the above methods, to methods for reconstituting the dry compositionand to uses thereof.

The present disclosure further relates to a paste having a desirablesoft consistency and uses thereof.

DESCRIPTION OF DRAWINGS

FIG. 1. Average reconstitution time+/−standard deviation of freeze-driedgelatine pastes comprising the different polyols of example 1. Thepastes have not been vacuum expanded prior to freeze-drying. Inclusionof different polyols in the freeze-dried paste composition resulted inspontaneous reconstitution of the pastes within about 30 seconds.

FIG. 2. Average reconstitution time+/−standard deviation of thelyophilised and vacuum expanded lyophilised gelatine pastes of example3. Vacuum expansion greatly decreased the spontaneous reconstitutiontime of pastes comprising mannitol.

FIGS. 3 to 14 depict different embodiments of the method of the presentdisclosure involving vacuum expansion of the pastes prior to drying.

FIG. 3 shows two possible embodiments of a syringe for use as acontainer before the paste has been added. Concept 1 encompasses astandard single use syringe and concept 2 encompasses a single usesyringe with a lyophilisation bypass in the syringe body. The pressurevalve is closed.

FIG. 4 shows the syringes of concept 1 and 2 with an amount of paste.

FIG. 5 shows a syringe fitted with a lyophilisation plunger comprising abypass (lyo plunger; concept 1) or a syringe comprising a bypass in thesyringe body being fitted with a standard plunger (concept 2). Thebypasses of both concept 1 and 2 allow for gaseous communication betweenthe product chamber and the outside of the container. Application of lowvacuum results in expansion of the paste, i.e. the volume of the pasteis greater than before application of vacuum.

FIG. 6 shows the syringes of concepts 1 and 2 after the paste has beenfrozen. Freezing results in a locked expanded paste structure.

FIG. 7 shows the syringes of concepts 1 and 2 undergoing vacuumfreeze-drying. Freeze-drying does not alter the volume of the frozenpaste.

FIG. 8 shows the syringes of concepts 1 and 2, wherein the bypasses havebeen closed with a collapsible shelf. The syringes contain the dry pastein a product chamber with vacuum.

FIG. 9 shows the syringes of concepts 1 and 2 after the vacuum in thefreeze-dryer has been released. The vacuum inside the product chamberand the atmospheric pressure outside the product chamber causes theplunger to shift until it comes into contact with the dry paste product.

FIG. 10 shows the syringes of concepts 1 and 2 after assembly of aplunger rod and flanges.

FIG. 11 shows the syringe of concept 1 being sterilised by irradiation.

FIG. 12 shows two different embodiments for reconstituting the drypaste. In a first embodiment (top), the syringe is fitted to a plasticbag holding sterile H₂O or saline. In a second embodiment (bottom), thesyringe is fitted to a plastic container holding sterile H₂O or saline,wherein the plastic container is fitted with a movable plunger.

FIG. 13 shows the two embodiments from FIG. 12 after the valve has beenopened. Opening of the valve results in the liquid automatically beingdrawn into the product chamber due to the pressure difference betweenthe product chamber (low pressure) and the liquid container (normalpressure). The paste is spontaneously reconstituted upon contact withthe liquid. Mechanical mixing is not required before use of the paste.

FIG. 14 depicts a ready to use paste within a syringe fitted with anapplicator tip.

FIG. 15 shows a correlation between the pressure used for vacuumexpanding a gelatine paste and the density of the final dry pastecomposition: The lower the pressure; the lower the density of the drycomposition.

FIGS. 16a-d show perspective views of the barrel of one embodiment ofthe presently disclosed syringe.

FIGS. 17a-b show perspective proximal views of two different embodimentsof the barrel of the presently disclosed syringe.

FIGS. 18a-b are cut-through side view illustrations of the barrel of oneembodiment of the presently disclosed syringe, with the pressure valvein two different positions.

FIG. 19a shows another embodiment of a pressure valve.

FIG. 19b shows a frontal view of another embodiment of the pressurechamber of the presently disclosed syringe with the pressure valve fromFIG. 19 a.

FIGS. 19c-d show cut-through frontal view of the configuration of thepressure valve from FIG. 19a inside the pressure chamber from FIG. 19 b.

FIGS. 20a-b are cut-through side view illustrations of the pressurevalve from FIG. 19a inside the pressure chamber from FIG. 19.

FIGS. 20c-d are perspective view illustrations of the barrel with thepressure valve and pressure chamber from FIG. 19.

FIG. 21 shows the average reconstitution time+/−standard deviation ofdried gelatine paste compositions comprising different amounts ofmannitol (% w/w in wet paste) with and without vacuum expansion. Vacuumexpansion greatly decreased the spontaneous reconstitution time of thedried pastes, which is even further decreased by increasingconcentrations of mannitol in the dried pastes.

FIG. 22 shows the reconstitution time+/−standard deviation of vacuumexpanded dried gelatine paste compositions with and without PEG (wt % inwet paste). PEG decreased the reconstitution time as compared to vacuumexpanded compositions without PEG.

FIG. 23 shows the consistency of pastes reconstituted from drycompositions comprising different concentrations of NaHCO₃ (Example 7).The results show that the consistency of the pastes softens as theconcentration of NaHCO₃ in the dry composition increases.

The drawings are exemplary only and should not be construed as limitingthe scope of the invention.

Definitions

“Ambient pressure” is herein used interchangeably with the term“atmospheric pressure”. It is the pressure in the surrounding area, i.e.the pressure in the location in which a process takes place.

“Bar” (unit). The bar is a non-SI unit of pressure, defined as exactlyequal to 100,000 Pa. It is about equal to the atmospheric pressure onEarth at sea level.

A “bioactive agent” is any agent, drug, compound, composition of matteror mixture which provides some pharmacologic, often beneficial, effectthat can be demonstrated in vivo or in vitro. An agent is thusconsidered bioactive if it has interaction with or effect on a celltissue in the human or animal body. As used herein, this term furtherincludes any physiologically or pharmacologically active substance thatproduces a localized or systemic effect in an individual. Bioactiveagents may be a protein, such as an enzyme. Further examples ofbioactive agents include, but are not limited to, agents comprising orconsisting of an oligosaccharide, a polysaccharide, an optionallyglycosylated peptide, an optionally glycosylated polypeptide, anoligonucleotide, a polynucleotide, a lipid, a fatty acid, a fatty acidester and secondary metabolites. It may be used either prophylactically,therapeutically, in connection with treatment of an individual, such asa human or any other animal. The term “bioactive agent” as used hereindoes not encompass cells, such as eukaryotic or prokaryotic cells.

“Biocompatible” refers to a material's ability to perform its intendedfunction without eliciting any substantial undesirable local or systemiceffects in the host.

“Biologically absorbable” or “resorbable” are terms which in the presentcontext are used to describe that the materials of which the said powderare made can be degraded in the body to smaller molecules having a sizewhich allows them to be transported into the blood stream. By saiddegradation and absorption the said powder materials will gradually beremoved from the site of application. For example, gelatine can bedegraded by proteolytic tissue enzymes to absorbable smaller molecules,whereby the gelatine, when applied in tissues, typically is absorbedwithin about 4-6 weeks and when applied on bleeding surfaces and mucousmembranes typically within 3-5 days.

“Carbonate salt” as used herein includes carbonate (CO₃ ²⁻) andbicarbonate (HCO₃)⁻ salts.

“Expansion” is herein defined as an increase in volume and a decrease indensity. Thus, if a material is said to be expanded, the total volume ofthe material is greater than before the expansion without affecting thetotal weight of the material.

A “gel” is a solid, jelly-like material that can have properties rangingfrom soft and weak to hard and tough. Gels are defined as asubstantially dilute cross-linked system, which exhibits no flow when inthe steady-state. By weight, gels are mostly liquid, yet they behavelike solids due to a three-dimensional cross-linked network within theliquid. It is the crosslinks within the fluid that give a gel itsstructure (hardness) and contribute to stickiness (tack). In this waygels are a dispersion of molecules of a liquid within a solid in whichthe solid is the continuous phase and the liquid is the discontinuousphase. A gel is not a paste or slurry. For example, non-crosslinkedgelatin particles are soluble and may form a gel upon contact with anaqueous medium such as water. A gel does not have pores comprisingexpandable gas or air.

“Haemostasis” is a process which causes bleeding to diminish or stop.Haemostasis occurs when blood is present outside of the body or bloodvessels and is the instinctive response for the body to stop bleedingand loss of blood. During haemostasis three steps occur in a rapidsequence. Vascular spasm is the first response as the blood vesselsconstrict to allow less blood to be lost. In the second step, plateletplug formation, platelets stick together to form a temporary seal tocover the break in the vessel wall. The third and last step is calledcoagulation or blood clotting. Coagulation reinforces the platelet plugwith fibrin threads that act as a “molecular glue”. Accordingly, ahaemostatic compound is capable of stimulating haemostasis.

“International Unit (IU)”. In pharmacology, the International Unit is aunit of measurement for the amount of a substance, based on biologicalactivity or effect. It is abbreviated as IU, UI, or as IE. It is used toquantify vitamins, hormones, some medications, vaccines, blood products,and similar biologically active substances.

A “paste” according to the present disclosure has a malleable,putty-like consistency, such as toothpaste. A paste is a thick fluidmixture of pulverized solid/solid in powder form with a liquid. A pasteis a substance that behaves as a solid until a sufficiently large loador stress is applied, at which point it flows like a fluid, i.e. a pasteis flowable. Flowables conform efficiently to irregular surfaces uponapplication. Pastes typically consist of a suspension of granularmaterial in a background fluid. The individual grains are jammedtogether like sand on a beach, forming a disordered, glassy or amorphousstructure, and giving pastes their solid-like character. It is this“jamming together” that gives pastes some of their most unusualproperties; this causes paste to demonstrate properties of fragilematter. A paste is not a gel/jelly. A “slurry” is a fluid mixture of apowdered/pulverized solid with a liquid, such as water. Slurries behavein some ways like thick fluids, flowing under gravity and being capableof being pumped if not too thick. A slurry may functionally be regardedas a thin, watery paste, but a slurry generally contains more water thana paste. A paste according to the present disclosure has pores beingcompartments comprising an expandable gas, such as air. Substantiallywater-insoluble powder particles, such as cross-linked gelatineparticles, will form a paste upon mixing with an aqueous medium.

“Percentage”. If nothing else is indicated, the percentage is percentageby weight: % w/w or wt %.

Ratios are indicated as weight by weight (w/w).

A “reduced pressure” is herein considered a pressure below ambientpressure, i.e. a pressure below that of the pressure in the surroundingarea in which a certain process operates.

“Spontaneous”. The term “spontaneous” is used to describe phenomenaarising from internal forces or causes, which are independent ofexternal agencies or stimuli and which happen within a short period oftime, preferably within less than about 30 seconds, more preferredwithin less than about 20 seconds, even more preferred within less thanabout 10 seconds or within less than about 5 seconds, such as withinless than about 3 seconds, for example less than about 2 seconds.

“Vacuum” is herein defined as a region with a gaseous pressure less thanthe ambient pressure, i.e. the surrounding atmospheric pressure. At sealevel on Earth the atmospheric pressure is approximately 1 bar, i.e.1000 mbar at 25° C. The below table shows the approximate pressures in“low”, “medium” and “high” vacuum at sea level on earth in millibar(mbar).

pressure (mbar) Atmospheric pressure 1000 Low vacuum 1000 to 100 Mediumvacuum   100 to 0.001 High vacuum <0.001

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure provides a dry composition, which upon additionof an adequate amount of an aqueous medium forms a substantiallyhomogenous paste, which is soft and light (“fluffy” or airy”). The drycomposition is capable of reconstituting without any mechanical mixingrequired.

Reconstitution without mechanical mixing and a soft consistency of thereconstituted paste can be achieved by contacting an acid and a basewhich are capable of reacting with each other to produce a gas in thepresence of an aqueous medium. The acid and the base are capable ofreacting with each other when the dry composition is wetted, i.e. uponreconstitution of the dry composition.

In a preferred embodiment, the dry composition is prepared with acarbonate salt as the base. Upon addition of an aqueous mediumcomprising an acid, the acid reacts with the carbonate ion to createcarbonic acid, which readily decomposes to CO₂. The CO₂ gas expandsinside the paste, thereby allowing for efficient distribution of liquidinside the dry composition. The resulting paste has a soft desirableconsistency.

The advantages of the dry composition and the reconstituted pasteobtained by the methods of the present disclosure are numerous andinclude:

-   -   Less time is spent preparing the paste which means that bleeding        can be stopped faster.    -   Decreased risk of compromising the sterility of the paste during        preparation due to less handling steps.    -   Decreased risk of making mistakes during preparation of the        paste.    -   Optimal consistency of paste obtained every time.    -   Reliable and consistent reconstitution within a short time        period.    -   Bioactive agents, which are unstable in solution may be added to        the paste prior to drying and will thus be present in the dry        composition of the invention. For example, thrombin may be added        to the paste prior to drying, thereby avoiding the        time-consuming and error-prone thrombin dilution steps.    -   Minimises Operation Room costs since preparation of the        currently described product is so simple and fast that there is        no reason to pre-prepare haemostatic flowables before surgery        which may not be used.    -   Reconstituted paste has a soft consistency, which may be        desirable in certain types of surgeries.

All of the above factors lead to increased patient safety.

Biocompatible Polymer

A paste can be formed from a biocompatible polymer when thebiocompatible polymer is in powder form and the powder particles aresubstantially insoluble in the aqueous medium they are mixed with. Thus,the biocompatible polymer in powder form consists of substantiallywater-insoluble powder particles. Preferably, the agent is across-linked biocompatible polymer suitable for use in haemostasisand/or wound healing, such as a cross-linked haemostatic agent in powderform, for example a cross-linked gelatine powder. Cross-linking rendersthe biocompatible polymer substantially insoluble in an aqueous medium.

The biocompatible polymer in powder form consists of solid, porous ornon-porous particles of a biocompatible polymer suitable for use inhaemostasis and wound healing procedures.

In one embodiment, the composition of the present disclosure comprisesone or more biocompatible polymers in powder form, such as a singlebiocompatible polymer or a combination of two or more biocompatiblepolymers.

The biocompatible polymer of the present disclosure may be a biologic ora non-biologic polymer. Suitable biologic polymers include proteins,such as gelatin, collagen, albumin, hemoglobin, casein, fibrinogen,fibrin, fibronectin, elastin, keratin, and laminin; or derivatives orcombinations thereof. Particularly preferred is the use of gelatin orcollagen, more preferably gelatin. Other suitable biologic polymersinclude polysaccharides, such as glycosaminoglycans, starch derivatives,xylan, cellulose derivatives, hemicellulose derivatives, agarose,alginate, and chitosan; or derivatives or combinations thereof. Suitablenon-biologic polymers will be selected to be degradable by either of twomechanisms, i.e. (1) break down of the polymeric backbone or (2)degradation of side chains which result in aqueous solubility. Exemplarynonbiologic polymers include synthetics, such as polyacrylates,polymethacrylates, polyacrylamides, polyvinyl resins,polylactide-glycolides, polycaprolactones, and polyoxyethylenes; orderivatives or combinations thereof. Also combinations of differentkinds of polymers are possible.

In a preferred embodiment the biocompatible polymer is biologicallyabsorbable. Examples of suitable biologically absorbable materialsinclude gelatine, collagen, chitin, chitosan, alginate, cellulose,oxidised cellulose, polyglycolic acid, polyacetic acid and combinationsthereof. It will be understood that various forms thereof, such aslinear or cross-linked forms, salts, esters and the like are alsocontemplated for the present disclosure. In a preferred embodiment, thebiologically absorbable material is gelatine. Gelatine is highlybiologically absorbable. Furthermore, gelatine is highly biocompatible,meaning that it is non-toxic to an animal, such as a human being,when/if entering the blood stream or being in long-term contact withhuman tissues.

The gelatine typically originates from a porcine source, but mayoriginate from other animal sources, such as from bovine or fishsources. The gelatine may also be synthetically made, i.e. made byrecombinant means.

In a preferred embodiment the biocompatible polymer is cross-linked.Cross-linking usually renders the polymer substantially insoluble in anaqueous medium. Any suitable cross-linking methods known to a person ofskill may be used including both chemical and physical cross-linkingmethods.

In one embodiment of the present disclosure the polymer has beencross-linked by physical means, such as by dry heat. The dry heattreatment is usually performed at temperatures between 100° C. and 250°C., such as about 110° C. to about 200° C. In particular the temperaturemay be in the range of 110-160° C., e.g. in the range of 110-140° C., orin the range of 120-180° C., or in the range of 130-170° C., or in therange of 130-160° C., or in the range of 120-150° C. The period of timefor cross-linking may be optimised by a skilled person and is normally aperiod between about 10 minutes to about 12 hours, such as about 1 hourto about 10 hours, for example between about 2 hours to about 10 hours,such as between about 4 hours to about 8 hours, for example betweenabout 5 hours to about 7 hours, such as about 6 hours.

In another embodiment, the polymer has been cross-linked by chemicalmeans, i.e. by exposure to a chemical cross-linking agent. Examples ofsuitable chemical cross-linking agents include but are not limited toaldehydes, in particular glutaraldehyde and formaldehyde, acyl azide,caboiimides, hexamethylene diisocyanate, polyether oxide,1,4-butanedioldiglycidyl ether, tannic acid, aldose sugars, e.g.D-fructose, genipin and dye-mediated photo-oxidation. Specific compoundsinclude but are not limited toI-(3-dimethylaminopropyl)-3-ethylcarboiimide hydrochloride (EDC),dithiobis(propanoic dihydrazide) (DTP),I-ethyl-3-(3-dimethylamino-propyl)-carbodiimide (EDAC).

In a preferred embodiment, the biocompatible polymer is obtained fromcross-linked sponges of gelatine or collagen, in particular cross-linkedsponges of gelatine (such as the commercially available Spongostan®sponges and Surgifoam® sponges). The cross-linked sponges are micronizedby methods known in the art to obtain a cross-linked biocompatiblepolymer in powder form, such as by rotary bed, extrusion, granulationand treatment in an intensive mixer, or milling (e.g. by using a hammermill or a centrifugal mill).

Spongostan®/Surgifoam® available from Ethicon is a gelatine basedcross-linked absorbable haemostatic sponge. It absorbs >35 g of blood/gand within 4-6 weeks it is completely absorbed in the human body.

In one embodiment, the biocompatible polymer in powder form comprises orconsists of gelatine particles obtained from a micronized porousgelatine sponge, which has been cross-linked by dry heat treatment. Suchgelatine particles will be porous.

Micronized porous gelatine sponges may be prepared by mixing an amountof soluble gelatine with an aqueous medium in order to create a foamcomprising a discontinuous gas phase, drying said foam and crosslinkingthe dried foam by exposure to dry heat, thereby obtaining a drycrosslinked sponge. The obtained crosslinked sponge can be micronized bymethods known in the art. The gelatine foam usually has a gelatineconcentration from about 1% to 70% by weight, usually from 3% to 20% byweight. Drying is usually performed at about 20° C. to about 40° C. forabout 5 to 20 hours. The dried foam is usually crosslinked by exposureto a temperature of about 110° C. to about 200° C. for about 15 minutesto about 8 hours, such as at about 150° C. to about 170° C. for about 5to 7 hours.

In another embodiment, the biocompatible polymer comprises or consistsof cross-linked gelatine particles obtained from a gelatine hydrogel. Agelatine hydrogel may be prepared by dissolving an amount of gelatine inan aqueous buffer to form a non-cross-linked hydrogel, typically havinga solids content from 1% to 70% by weight, usually from 3% to 10% byweight. The gelatin is cross-linked, for example by exposure to eitherglutaraldehyde (e.g. 0.01% to 0.05% w/w, overnight at 0 DEG to 15 DEG C.in aqueous buffer), sodium periodate (e.g. 0.05 M, held at 0 DEG C. to15 DEG C. for 48 hours) or 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (“EDC”) (e.g., 0.5% to 1.5% w/w, overnight at roomtemperature), or by exposure to about 0.3 to 3 megarads of gamma orelectron beam radiation. The resulting crosslinked hydrogels may befragmented and dried to obtain a gelatine powder. Alternatively, gelatinparticles can be suspended in an alcohol, preferably methyl alcohol orethyl alcohol, at a solids content of 1% to 70% by weight, usually 3% to10% by weight, and cross-linked by exposure to a cross-linking agent,typically glutaraldehyde (e.g., 0.01% to 0.1% w/w, overnight at roomtemperature). When cross-linking with glutaraldehyde, the cross-linksare formed via Schiff bases which may be stabilized by subsequentreduction, e.g. by treatment with sodium borohydride. Aftercross-linking, the resulting granules may be washed in water andoptionally rinsed in an alcohol and dried to obtain a gelatine powder.In one embodiment, crosslinked gelatine particles are preparedessentially as described in U.S. Pat. No. 6,066,325. Such gelatineparticles will be non-porous.

The cross-linked powder particles are in one embodiment less thanapproximately 1000 microns in size, i.e. so that they are able to passthrough a 1×1 mm sieve.

In one embodiment at least 90% of the powder particles have a diameterof between 1 μm and 1200 μm.

In one embodiment, the average particle diameter is between 1 μm and1000 μm, such as between 10 μm and 800 μm, for example between 50 μm and600 μm, such as between 100 μm and 500 μm, for example between 200 μmand 400 μm, such as about 300 μm.

In some applications it is desirable to have a smaller particle size,whereby a smoother paste can be obtained. Thus in one embodiment, theaverage particle diameter is less than 100 μm, such as less than 50 μm,for example less than 30 μm, such as less than 20 μm, for example lessthan 10 μm. One example of an application where a smoother paste isdesirable is in the control of bone bleeding.

Particles of a certain size distribution can be achieved by passing apowdered composition through one or more sieves having a certain meshsize and collecting the powder which passes through and/or is retainedby a certain mesh size. For example, powder particles having a sizedistribution between approximately 200 μm and 1000 μm can be obtained bycollecting the powder which is able to pass through a 1×1 mm sieve butis retained by a 0.2×0.2 mm sieve.

In one embodiment, the paste obtained by mixing the biocompatiblepolymer in powder form and the aqueous medium comprises between about10% to about 60% of the biocompatible polymer, for example about 10% toabout 50% of the biocompatible polymer, such as about 10% to about 40%of the biocompatible polymer, for example about 10% to about 30% of thebiocompatible polymer, such as about 12% to about 25% of thebiocompatible polymer, for example about 14% to about 25% of thebiocompatible polymer, such as about 15% to about 25% of thebiocompatible polymer, for example about 16% to about 20% of thebiocompatible polymer, such as about 17% to about 20% of thebiocompatible polymer, for example about 18% to about 20% of thebiocompatible polymer.

In one embodiment, the paste obtained by mixing the biocompatiblepolymer in powder form and the aqueous medium comprises more than 10% ofthe biocompatible polymer, such as more than 15% of the biocompatiblepolymer, for example more than 16% of the biocompatible polymer, such asmore than 17% of the biocompatible polymer, for example more than 18% ofthe biocompatible polymer, such as more than 19% of the biocompatiblepolymer, for example more than 20% of the biocompatible polymer.

In one embodiment, the paste obtained by mixing the biocompatiblepolymer in powder form and the aqueous medium comprises less than 40% ofthe biocompatible polymer, such as less than 30% of the biocompatiblepolymer, for example less than 25% of the biocompatible polymer, such asless than 20% of the biocompatible polymer.

In a preferred embodiment, the paste obtained by mixing thebiocompatible polymer in powder form and the aqueous medium comprisesbetween about 10% to about 30% of the biocompatible polymer, morepreferred between about 15% to about 25% of the biocompatible polymer,such as about 20% of the biocompatible polymer.

After drying, the composition comprises between about 40% and 80% of thebiocompatible polymer, such as between about 45% and 80% of thebiocompatible polymer, for example between about 50% and 80% of thebiocompatible polymer, such as between about 55% and 80% of thebiocompatible polymer.

In one embodiment, the dry composition comprises between about 40% and80% of the biocompatible polymer, such as between about 45% and 75% ofthe biocompatible polymer, for example between about 50% and 70% of thebiocompatible polymer.

In one embodiment, the dry composition of the present disclosurecomprises more than about 30% of the biocompatible polymer, such as morethan about 40% of the biocompatible polymer, for example more than about45% of the biocompatible polymer, such as more than about 50% of thebiocompatible polymer, for example more than about 55% of thebiocompatible polymer, such as more than about 60% of the biocompatiblepolymer, for example more than about 65% of the biocompatible polymer,such as more than about 70% of the biocompatible polymer, for examplemore than about 75% of the biocompatible polymer, such as more thanabout 80% of the biocompatible polymer.

In one embodiment, the dry composition of the present disclosurecomprises less than about 80% of the biocompatible polymer, such as lessthan about 70% of the biocompatible polymer, for example less than about65% of the biocompatible polymer, such as less than about 60% of thebiocompatible polymer, for example less than about 55% of thebiocompatible polymer, such as less than about 50% of the biocompatiblepolymer.

Acid-Base Reactions Capable of Forming a Gas

Introduction of a gas into the reconstituted paste without mechanicalmixing is achieved by the presence of an alkaline compound and an acidiccompound, wherein said alkaline compound and said acidic compound arecapable of producing a gas in the presence of an aqueous medium.

When the dry composition of the present disclosure is reconstituted byadding an aqueous medium, a gas is produced as a result of the reactionof the acidic compound and the alkaline compound. The gas expands insidethe composition being reconstituted resulting in a paste having a softand light consistency without the need for mechanically introducing airinto the composition, e.g. by transfer of the composition between twoconnected syringes.

The release of a gas upon wetting of the dry composition can be achievedin at least three alternative ways:

-   -   1. By preparing a dry composition comprising an alkaline        compound and reconstituting with an aqueous medium comprising an        acidic compound.    -   2. By preparing a dry composition comprising an acidic compound        and reconstituting with an aqueous medium comprising an alkaline        compound.    -   3. By preparing a dry composition comprising both an alkaline        compound and an acidic compound and reconstituting with an        aqueous medium.

For all three options, the alkaline compound and the acidic compoundmust be capable of reacting with each other to produce a gas in thepresence of an aqueous medium.

For the third alternative it is important that the alkaline compound andthe acidic compound are not contacted with an aqueous medium before gasrelease is desired, i.e. before reconstitution. The third alternativecan e.g. be achieved by mixing an alkaline compound into the wet paste,drying the paste and adding an acidic compound in dry form to the driedpaste or the reverse, by mixing an acidic compound into the wet paste,drying the paste and adding an alkaline compound in dry form to thedried paste. The alkaline compound and the acidic compound will notreact in dry conditions and will only react upon wetting of thecomposition. The acidic or alkaline compound added in dry form should beat least partially soluble in water.

In one embodiment, the dry composition comprises from about 0.1% toabout 10% of an alkaline compound, for example from about 0.5% to about8% of an alkaline compound, such as from about 1% to about 6% of analkaline compound or from about 1% to about 5% of an alkaline compound.Optionally the dry composition further comprises from about 0.1% toabout 10% of an acidic compound, for example from about 0.5% to about 8%of an acidic compound, such as from about 1% to about 5% of an acidiccompound, wherein the acidic compound is added in dry form after thepaste has been dried.

In one embodiment, the dry composition comprises at least 1% of analkaline compound, for example at least 1.5% of an alkaline compound,such as at least 2% of an alkaline compound, for example at least 2.5%of an alkaline compound, such as at least 3% of an alkaline compound,for example at least 3.5% of an alkaline compound, such as at least 4%of an alkaline compound, for example at least 4.5% of an alkalinecompound, such as at least 5% of an alkaline compound. Optionally thedry composition further comprises an acidic compound as described above.

In one embodiment, the dry composition comprises less than 10% of analkaline compound, for example less than 8% of an alkaline compound,such as less than 7% of an alkaline compound, for example less than 6%of an alkaline compound, such as less than 5% of an alkaline compound,for example less than 4% of an alkaline compound, such as less than 3%of an alkaline compound. Optionally the dry composition furthercomprises an acidic compound as described above.

In one embodiment, the dry composition comprises from about 0.1% toabout 10% of an acidic compound, for example from about 0.5% to about 8%of an acidic compound, such as from about 0.5% to about 5% of an acidiccompound or from about 1% to about 5% of an acidic compound. Optionally,the dry composition further comprises from about 0.1% to about 10% of analkaline compound, for example from about 0.5% to about 8% of analkaline compound, such as from about 1% to about 5% of an alkalinecompound, wherein the alkaline compound is added in dry form after thepaste has been dried.

In one embodiment, the dry composition comprises at least 0.1% of anacidic compound, for example at least 0.2% of an acidic compound, suchas at least 0.3% of an acidic compound, for example at least 0.4% of anacidic compound, for example at least 0.5% of an acidic compound, suchas at least 0.6% of an acidic compound, for example at least 0.7% of anacidic compound, such as at least 0.8% of an acidic compound, forexample at least 0.9% of an acidic compound, such as at least 1.0% of anacidic compound, for example at least 1.5% of an acidic compound.Optionally the dry composition further comprises an alkaline compound asdescribed above.

In one embodiment, the dry composition comprises less than 10% of anacidic compound, for example less than 8% of an acidic compound, such asless than 7% of an acidic compound, for example less than 6% of anacidic compound, such as less than 5% of an acidic compound, for exampleless than 4% of an acidic compound, such as less than 3% of an acidiccompound. Optionally the dry composition further comprises an acidiccompound as described above.

In a preferred embodiment, the gas produced is carbon dioxide (CO₂). Oneway of producing CO₂ is by contacting a carbonate salt with an acidiccompound in the presence of an aqueous medium. Thus, in a preferredembodiment, the alkaline compound is a carbonate salt, even morepreferred a pharmaceutically acceptable carbonate salt.

Upon contact of a carbonate salt with an aqueous medium comprising anacidic compound, i.e. an acidic solution, the carbonate in the drycomposition will react with the acid to create carbonic acid, whichreadily decomposes to CO₂. The CO₂ gas expands inside the compositionbeing reconstituted, thereby ensuring a soft and light consistency ofthe reconstituted paste. For example, reaction of sodium bicarbonate(also known as sodium hydrogen carbonate or common baking soda) and anacid produces sodium chloride and carbonic acid, which readilydecomposes to carbon dioxide and water:

NaHCO₃+HCl→NaCl+H₂CO₃

H₂CO₃→H₂O+CO₂(g)

For example, if sodium bicarbonate is contacted with acetic acid in anaqueous medium, the result will be sodium acetate, water, and carbondioxide:

NaHCO₃+CH₃COOH→CH₃COONa+H₂O+CO₂(g)

In one embodiment, the carbonate salt is selected from the groupconsisting of sodium bicarbonate (NaHCO₃), sodium carbonate (Na₂CO₃),potassium bicarbonate (KHCO₃), potassium carbonate (K₂CO₃), calciumbicarbonate (Ca(HCO₃)₂), calcium carbonate (CaCO₃), magnesium carbonate(MgCO₃), magnesium bicarbonate (Mg(HCO₃)₂), ammonium bicarbonate(NH₄HCO₃), ammonium carbonate ((NH₄)₂CO₃), gadolinium bicarbonate(Gd(HCO₃)₃, gadolinium carbonate (Gd₂(CO₃)₃), lithium bicarbonate(LiHCO₃), lithium carbonate (LiCO₃), rubidium bicarbonate (RbHCO₃),rubidium carbonate (Rb₂CO₃), zinc carbonate (ZnCO₃), zinc bicarbonate(Zn(HCO₃)₂, iron (II) carbonate (FeCO₃), iron (II) bicarbonate(Fe(HCO₃)₂), silver carbonate (Ag₂CO₃), silver bicarbonate (AgHCO₃),gold (III) carbonate Au₂(CO₃)₃, gold (I) carbonate (Au₂CO₃) and mixturesthereof.

In one embodiment, the cation of the carbonate salt is a metal.

In one embodiment, the cation of the carbonate salt is sodium, i.e. thecarbonate salt is sodium bicarbonate or sodium carbonate, preferablysodium bicarbonate.

In one embodiment, the cation of the carbonate salt is calcium, i.e. thecarbonate salt is calcium bicarbonate or calcium carbonate. Sincecalcium is an activator of thrombin, the presence of calcium in thereconstituted paste may be beneficial in embodiments comprising thrombinas it may lead to enhanced thrombin activity.

In one embodiment, the cation of the carbonate salt is potassium, i.e.the carbonate salt is potassium bicarbonate (KHCO₃) or potassiumcarbonate (K₂CO₃).

In one embodiment, the carbonate salt is at least partially soluble inwater. For instance, the carbonate salt has a solubility in water at 20°C. and at 1 atmosphere pressure above about 1 g/100 g water, for exampleat least about 5 g/100 g water. For instance, sodium bicarbonate has asolubility of about 9.6 g/100 g water at 20° C. and at 1 atmospherepressure. When a carbonate salt is added in dry form to a drycomposition comprising an acidic compound it is important that thecarbonate salt is at least partially soluble in water for it toeffectively come into contact with the acidic compound distributedwithin the dry composition when the composition is wetted, i.e.reconstituted.

In other embodiments, the carbonate salt is essentially not soluble inwater. For instance, calcium carbonate has a solubility of less than0.001 g/100 g water at 20° C. and at 1 atmosphere pressure and silvercarbonate has a solubility of less than 0.01 g/100 g water at 20° C. andat 1 atmosphere pressure. When a dry composition is prepared with acarbonate salt essentially homogenously distributed therein, i.e. byadding the carbonate salt to the paste before drying, the carbonate saltdoes not have to be soluble in water.

In one embodiment, the dry composition comprises from about 0.1% toabout 10% of a carbonate salt, for example from about 0.5% to about 8%of a carbonate salt, such as from about 1% to about 6% or 1% to about 5%of a carbonate salt. Optionally, the dry composition further comprisesan acidic compound in dry form.

When a dry composition comprising a carbonate salt is contacted with anacidic compound in the presence of an aqueous medium, CO₂ will beproduced as explained above. The dry composition comprising a carbonatesalt may either be reconstituted with an aqueous medium comprising anacidic compound, i.e. an acidic solution (1^(st) alternative) or if thedry composition comprising a carbonate salt is further added an acidiccompound in dry form after drying, the dry composition may bereconstituted with an aqueous medium which neither comprises an acidicnor an alkaline compound (3^(rd) alternative). In the latter case, anacidic solution will form upon addition of the aqueous medium as theacid will dissolve in the aqueous medium.

In one embodiment, the dry composition comprising a carbonate salt isreconstituted by addition of an acidic solution having a pH in the rangeof from about 1 to about 6, such as a pH from about 1.5 to about 5, forexample a pH from about 2 to about 4. The optimal pH of thereconstitution liquid can be determined by the skilled person bybalancing the need for efficient gas development during reconstitutionand the desire to have a reconstituted paste with a pH as close to 7 aspossible.

In one embodiment, the dry composition comprising an alkaline compound,such as a carbonate salt is reconstituted by addition of an acidicsolution comprising between about 1% to about 10% of an acidic compound,such as from about 1% to about 8% of an acidic compound, for examplefrom about 1.5% to about 6% of an acidic compound, such as from about 2%to about 5% of an acidic compound, for example from about 2% to about 4%of an acidic compound.

In one embodiment the acidic solution has a pH of from about 1 to about4, such as from about 1 to about 3, for example from about 1.5 to about2.5, such as about 2.

In one embodiment the acidic solution has a pH lower than about 4, suchas lower than about 3, for example lower than about 2.5.

Preferably, the alkaline and acidic compounds used in the presentinvention are physiologically acceptable compounds. The termphysiologically acceptable is used interchangeably herein with the termpharmaceutically acceptable.

In one embodiment, the acidic compound in the reconstitution liquid isselected from the group consisting of acetic acid, citric acid, tartaricacid and oxalic acid.

In one embodiment, the acidic compound is acetic acid.

In one embodiment, the acidic compound is citric acid.

In one embodiment, the acidic compound is tartaric acid.

In one embodiment, the acidic compound is oxalic acid.

According to the second alternative above, a dry composition comprisingan acidic compound is prepared and said dry composition is contactedwith alkaline compound upon reconstitution of the dry composition. Forinstance, the dry composition comprising an acidic compound can bereconstituted with an aqueous medium comprising an alkaline compound,for instance an aqueous medium comprising a carbonate salt. If the drycomposition comprising an acidic compound is further added an alkalinecompound in dry form after drying of the composition, the drycomposition may be reconstituted with an aqueous medium which neithercomprises an acidic nor an alkaline compound (3^(rd) alternative). It isimportant, however, that the alkaline compound is at least partiallysoluble in water to allow for the alkaline compound to effectively comeinto contact with the acidic compound distributed within the drycomposition upon wetting of the composition.

In one embodiment, the dry composition comprises an acidic compoundselected from the group consisting of acetic acid, citric acid, oxalicacid and tartaric acid. This composition may suitably be reconstitutedby addition of a solution comprising an alkaline compound such as acarbonate salt.

In one embodiment the dry composition comprises acetic acid.

In one embodiment the dry composition comprises citric acid.

In one embodiment the dry composition comprises oxalic acid.

In one embodiment the dry composition comprises tartaric acid.

The dry composition comprising an acidic compound may be reconstitutedby addition of an alkaline solution comprising between about 1% to about10% of an alkaline compound, such as from about 1% to about 8% of analkaline compound, for example from about 1.5% to about 6% of analkaline compound, such as from about 2% to about 5% of an alkalinecompound, for example from about 2% to about 4% of an alkaline compound.

In one embodiment the alkaline solution has a pH of from about 7.5 toabout 9, such as from about 8 to about 9, for example from about 8 toabout 9.5.

In one embodiment the alkaline solution has a pH higher than about 7.5,such as higher than about 7.8, for example higher than about 8.0, suchas higher than about 8.5.

In an alternative embodiment, the reaction of an alkaline compound andan acidic compound causes the production of a noble gas, such as helium(He), neon (Ne) or argon (Ar).

In yet another embodiment, the reaction of an alkaline compound and anacidic compound causes the production of hydrogen (H₂), nitrogen (N₂) oroxygen (O₂).

Aqueous Medium

An aqueous medium is used in the method of the present disclosure forinitially preparing the paste, which is subsequently dried to obtain adry composition. An aqueous medium is also used for reconstituting thedry composition.

The aqueous medium of the present disclosure may be any aqueous mediumsuitable for preparing a paste known to a person of skill, e.g. water orsaline. The water may for example be WFI (Water For Injection). Theaqueous medium is preferably sterile and compatible with surgical use.

The aqueous medium of the present disclosure is in one embodiment asaline solution.

In one embodiment, the aqueous medium is a calcium chloride solution.

In one embodiment, the aqueous medium is water.

The aqueous medium is initially mixed with the agent in powder form insufficient amounts to obtain a wet paste. For procedural efficiency, itis sometimes desirable that the paste prior to drying contains lesswater, i.e. is thicker, than a paste intended for e.g. surgical usewould be so that less water has to be removed in the drying process.

In one embodiment, the paste of the present disclosure prior to dryingcomprises less than 99% of water, preferably less than 95% of water.

In one embodiment, the paste of the present disclosure prior to dryingcomprises between about 50% to about 90% of water, such as between about55% to about 85% of water, for example between about 60% to about 80% ofwater, such as about 70% of water.

After drying, the dry composition comprises less than about 5% of water,such as less than about 3% of water, preferably less than about 2% ofwater, more preferred less than about 1.5% of water, even more preferredless than about 1% of water or even less. Hence, in one embodiment, thedry composition comprises from about 0.1 to about 5% water, such as fromabout 0.1% to about 2% water.

A low residual water content in the haemostatic composition after dryingis desirable as it decreases the risk of microbial growth in the drycomposition. Furthermore, a low residual water content is essential ifthe composition comprises bioactive agents that are unstable in aqueousconditions, such as e.g. thrombin. If thrombin is present in thecomposition of the present disclosure, the residual water content in thedried composition is preferably less than about 3% water, more preferredless than 2% water, such as less than 1% water.

In one embodiment, the residual water content in the dry composition isabout 0.5% or less. Such low residual water content is possible withe.g. industrial freeze-drying apparatuses.

Hydrophilic Compounds

In one embodiment, the dry composition of the present disclosurecomprises one or more hydrophilic compounds. Hydrophilic compoundsusually contain polar or charged functional groups, rendering themsoluble in water. Inclusion of one or more hydrophilic compounds in thepaste prior to drying of said paste has a beneficial effect on thewettability of the paste, thus enhancing reconstitution efficiency andreconstitution rate of the dry composition.

In one embodiment, the hydrophilic compound is a hydrophilic polymer.The hydrophilic polymer may be natural or synthetic, linear or branched,and have any suitable length.

In one embodiment, the hydrophilic polymer is selected from the groupconsisting of Polyethylenimine (PEI), Poly(ethylene glycol) (PEG),Poly(ethylene oxide), Poly(vinyl alcohol) (PVA), Poly(styrenesulfonate)(PSS), Poly(acrylic acid) (PAA), Poly(allylamine hydrochloride) andPoly(vinyl acid). In one embodiment, the hydrophilic compound ispolyethylene glycol (PEG).

In one embodiment, the hydrophilic compound is selected from the groupconsisting of Cetylpyridinium Chloride, Docusate Sodium, Glycine,Hypromellose, Hypromellose, Phthalate, Lechitin, Phospholipids,Poloxamer, Polyoxyethylene Alkyl Ethers, Polyoxyethylene Castor OilDerivatives, Polyoxyethylene Sorbitan Fatty Acid Esters, PolyoxyethyleneStearates, Polyvinyl Alcohol, Sodium Lauryl Sulfate, Sorbitan Esters(Sorbitan Fatty Acid Esters) and Tricaprylin.

In one embodiment, the hydrophilic compound is not a polymer.

In one embodiment, the hydrophilic compound is not a macromolecule.

In one embodiment, the hydrophilic compound has a molecular weight ofless than 1000 Da, such as less than 500 Da.

In one embodiment, the hydrophilic compound is an oligomer, such as anoligomer consisting of less than 10 monomeric subunits, for example lessthan 5 monomeric subunits.

In one embodiment, the hydrophilic compound is a dimer, a trimer or atetramer.

In one embodiment, the hydrophilic compound is a monomer.

In one embodiment, the hydrophilic compound comprises less than 20 Catoms, such as 18 C atoms or less or 12 C atoms or even less, such as 6C atoms.

In a preferred embodiment, the hydrophilic compound is a polyol. Thus,according to one embodiment, one or more polyols may be included in thepaste prior drying of the paste. Polyols greatly enhance thereconstitution rate of the dry paste composition and also play a role inensuring an optimal consistency of the reconstituted paste.

A polyol as defined herein is a compound with multiple hydroxylfunctional groups.

Polyols include sugars (mono-, di- and polysaccharides) and sugaralcohols and derivatives thereof. Preferably, the polyol is not apolysaccharide.

Monosaccharides include but are not limited to glucose, fructose,galactose, xylose and ribose.

Disaccharides include but are not limited to sucrose (saccharose),lactulose, lactose, maltose, trehalose and cellobiose.

Polysaccharides include but are not limited to starch, glycogen,cellulose and chitin.

A sugar alcohol, also known as a polyalcohol is a hydrogenated form ofcarbohydrate, whose carbonyl group (aldehyde or ketone, reducing sugar)has been reduced to a primary or secondary hydroxyl group (hence thealcohol). Sugar alcohols have the general formula H(HCHO)_(n+1)H,whereas sugars have H(HCHO)_(n)HCO. Some common sugar alcohols which maybe used in the method of the present disclosure include but are notlimited to: Glycol (2-carbon), Glycerol (3-carbon), Erythritol(4-carbon), Threitol (4-carbon), Arabitol (5-carbon), Xylitol(5-carbon), Ribitol (5-carbon), Mannitol (6-carbon), Sorbitol(6-carbon), Dulcitol (6-carbon), Fucitol (6-carbon), Iditol (6-carbon),Inositol (6-carbon; a cyclic sugar alcohol), volemitol (7-carbon),Isomalt (12-carbon), Maltitol (12-carbon), Lactitol (12-carbon),Polyglycitol.

In one embodiment, the dry composition comprises a single hydrophiliccompound, such as a single polyol.

In one embodiment, the dry composition comprises more than onehydrophilic compound, such as two, three, four, five, six or even moredifferent hydrophilic compounds.

In a preferred embodiment, the hydrophilic compound is a polyol.

In one embodiment, the dry composition comprises two polyols, forexample mannitol and glycerol or trehalose and a glycol.

In one embodiment, the dry composition comprises one or more sugaralcohols, such as one or more sugar alcohols selected from the groupconsisting of Glycol, Glycerol, Erythritol, Threitol, Arabitol, Xylitol,Ribitol, Mannitol, Sorbitol, Dulcitol, Fucitol, Iditol, Inositol,volemitol, Isomalt, Maltitol, Lactitol, Polyglycitol.

In one embodiment, the dry composition comprises one or more sugaralcohols and one or more sugars, such as one sugar alcohol and onesugar.

In one embodiment, the dry composition comprises one sugar alcohol andoptionally one or more additional hydrophilic compounds, such as one ormore polyols, which may be either sugar alcohols or sugars.

In one embodiment, the dry composition does not comprise a sugar as theonly polyol.

In one embodiment of the invention, the dry composition comprisesmannitol.

In one embodiment of the invention, the dry composition comprisessorbitol.

In one embodiment of the invention, the dry composition comprisesglycerol.

In one embodiment of the invention, the dry composition comprisestrehalose.

In one embodiment of the invention, the dry composition comprisesglycol, such as propylene glycol.

In one embodiment of the invention, the dry composition comprisesxylitol.

In one embodiment of the invention, the dry composition comprisesmaltitol.

In one embodiment of the invention, the dry composition comprisessorbitol.

In one embodiment the paste according to the invention prior to dryingcomprises from about 1% to about 40% of one or more hydrophiliccompounds, for example from about 1% to about 30% of one or morehydrophilic compounds, such as from about 1% to about 25% of one or morehydrophilic compounds, for example from about 1% to about 20% of one ormore hydrophilic compounds, such as from about 1% to about 15% of one ormore hydrophilic compounds, such as from about 1% to about 14% of one ormore hydrophilic compounds, for example from about 1% to about 13% ofone or more hydrophilic compounds, such as from about 1% to about 12% ofone or more hydrophilic compounds, for example from about 1% to about11% of one or more hydrophilic compounds, such as about 1% to about 10%of one or more hydrophilic compounds.

In one embodiment the paste according to the invention prior to dryingcomprises from about 2% to about 40% of one or more hydrophiliccompounds, for example from about 2% to about 30% of one or morehydrophilic compounds, such as from about 2% to about 25% of one or morehydrophilic compounds, for example from about 2% to about 20% of one ormore hydrophilic compounds, such as from about 2% to about 18% of one ormore hydrophilic compounds, for example from about 2% to about 17% ofone or more hydrophilic compounds, such as from about 2% to about 16% ofone or more hydrophilic compounds, for example from about 2% to about15% of one or more hydrophilic compounds, such as from about 2% to about14% of one or more hydrophilic compounds, for example from about 2% toabout 13% of one or more hydrophilic compounds, such as from about 2% toabout 12% of one or more hydrophilic compounds, for example from about2% to about 11% of one or more hydrophilic compounds, such as about 2%to about 10% of one or more hydrophilic compounds.

In one embodiment the paste according to the invention prior to dryingcomprises from about 3% to about 40% of one or more hydrophiliccompounds, for example from about 3% to about 30% of one or morehydrophilic compounds, such as from about 3% to about 25% of one or morehydrophilic compounds, for example from about 3% to about 20% of one ormore hydrophilic compounds, such as from about 3% to about 18% of one ormore hydrophilic compounds, for example from about 3% to about 17% ofone or more hydrophilic compounds, such as from about 3% to about 16% ofone or more hydrophilic compounds, for example from about 3% to about15% of one or more hydrophilic compounds, such as from about 3% to about14% of one or more hydrophilic compounds, for example from about 3% toabout 13% of one or more hydrophilic compounds, such as from about 3% toabout 12% of one or more hydrophilic compounds, for example from about3% to about 11% of one or more hydrophilic compounds, such as about 3%to about 10% of one or more hydrophilic compounds.

In one embodiment the paste according to the invention prior to dryingcomprises from about 4% to about 40% of one or more hydrophiliccompounds, for example from about 4% to about 30% of one or morehydrophilic compounds, such as from about 4% to about 25% of one or morehydrophilic compounds, for example from about 4% to about 20% of one ormore hydrophilic compounds, such as from about 4% to about 18% of one ormore hydrophilic compounds, for example from about 4% to about 17% ofone or more hydrophilic compounds, such as from about 4% to about 16% ofone or more hydrophilic compounds, for example from about 4% to about15% of one or more hydrophilic compounds, such as from about 4% to about14% of one or more hydrophilic compounds, for example from about 4% toabout 13% of one or more hydrophilic compounds, such as from about 4% toabout 12% of one or more hydrophilic compounds, for example from about4% to about 11% of one or more hydrophilic compounds, such as about 4%to about 10% of one or more hydrophilic compounds.

In one embodiment, the paste according to the invention prior to dryingcomprises more than about 5% of one or more hydrophilic compounds, hencein one embodiment the paste according to the invention prior to dryingcomprises from about 5% to about 40% of one or more hydrophiliccompounds, for example from about 5% to about 30% of one or morehydrophilic compounds, such as from about 5% to about 25% of one or morehydrophilic compounds, for example from about 5% to about 20% of one ormore hydrophilic compounds, such as from about 5% to about 18% of one ormore hydrophilic compounds, for example from about 5% to about 17% ofone or more hydrophilic compounds, such as from about 5% to about 16% ofone or more hydrophilic compounds, for example from about 5% to about15% of one or more hydrophilic compounds, such as from about 5% to about14% of one or more hydrophilic compounds, for example from about 5% toabout 13% of one or more hydrophilic compounds, such as from about 5% toabout 12% of one or more hydrophilic compounds, for example from about5% to about 11% of one or more hydrophilic compounds, such as about 5%to about 10% of one or more hydrophilic compounds.

In one embodiment the paste according to the invention prior to dryingcomprises from about 6% to about 40% of one or more hydrophiliccompounds, for example from about 6% to about 30% of one or morehydrophilic compounds, such as from about 6% to about 25% of one or morehydrophilic compounds, for example from about 6% to about 20% of one ormore hydrophilic compounds, such as from about 6% to about 18% of one ormore hydrophilic compounds, for example from about 6% to about 17% ofone or more hydrophilic compounds, such as from about 6% to about 16% ofone or more hydrophilic compounds, for example from about 6% to about15% of one or more hydrophilic compounds, such as from about 6% to about14% of one or more hydrophilic compounds, for example from about 6% toabout 13% of one or more hydrophilic compounds, such as from about 6% toabout 12% of one or more hydrophilic compounds, for example from about6% to about 11% of one or more hydrophilic compounds, such as about 6%to about 10% of one or more hydrophilic compounds.

In one embodiment, the paste according to the invention prior to dryingcomprises more than about 1% of one or more hydrophilic compounds, suchas more than about 2% of one or more hydrophilic compounds, for examplemore than about 3% of one or more hydrophilic compounds, such as morethan about 4% of one or more hydrophilic compounds, for example morethan about 5% of one or more hydrophilic compounds, such as more thanabout 6% of one or more hydrophilic compounds, for example more thanabout 7% of one or more hydrophilic compounds, such as more than about8% of one or more hydrophilic compounds, for example more than about 9%of one or more hydrophilic compounds, such as more than about 10% of oneor more hydrophilic compounds.

After drying, the dry composition comprises from about 10% to about 60%of one or more hydrophilic compounds, such as from about 10% to about50% of one or more hydrophilic compounds, for example from about 10% toabout 50%, such as from about 10% to about 45% of one or morehydrophilic compounds, for example from about 10% to about 40%, such asfrom about 10% to about 35% of one or more hydrophilic compounds, forexample from about 10% to about 30% of one or more hydrophiliccompounds.

In one embodiment, the dry composition comprises from about 15% to about60% of one or more hydrophilic compounds, such as from about 15% toabout 50% of one or more hydrophilic compounds, for example from about15% to about 50%, such as from about 15% to about 45% of one or morehydrophilic compounds, for example from about 15% to about 40%, such asfrom about 15% to about 35% of one or more hydrophilic compounds, forexample from about 15% to about 30% of one or more hydrophiliccompounds.

In one embodiment, the dry composition comprises from about 20% to about60% of one or more hydrophilic compounds, such as from about 20% toabout 50% of one or more hydrophilic compounds, for example from about20% to about 50%, such as from about 20% to about 45% of one or morehydrophilic compounds, for example from about 20% to about 40%, such asfrom about 20% to about 30% of one or more hydrophilic compounds.

In one embodiment, the dry composition comprises from about 25% to about60% of one or more hydrophilic compounds, such as from about 25% toabout 50% of one or more hydrophilic compounds, for example from about25% to about 45% of one or more hydrophilic compounds, such as fromabout 25% to about 40% of one or more hydrophilic compounds, for examplefrom about 25% to about 35% of one or more hydrophilic compounds, suchas from about 25% to about 30% of one or more hydrophilic compounds.

In one embodiment, the dry composition comprises less hydrophiliccompounds than biocompatible polymer, i.e. the hydrophiliccompounds:biocompatible polymer ratio is less than 1:1, such as lessthan or about 0.9:1, for example less than or about 0.8:1, such as lessthan or about 0.7:1, for example less than or about 0.6:1, such as lessthan or about 0.5:1, such as less than or about 0.4:1, for example lessthan or about 0.3:1, such as less than or about 0.2:1, for example lessthan or about 0.1:1. The hydrophilic compounds:biocompatible polymerratio is the same in the paste prior to drying.

In one embodiment, the hydrophilic compounds:biocompatible polymer ratiois between about 0.1:1 and 1:1; such as between about 0.2:1 and 1:1, forexample between about 0.3:1 and 1:1, such as between about 0.4:1 and1:1. In one embodiment, the hydrophilic compounds:biocompatible polymerratio is between about 0.1:1 and 0.8:1; such as between about 0.1:1 and0.7:1, for example between about 0.1:1 and 0.6:1, such as between about0.1:1 and 0.5:1, for example between 0.1:1 and 0.45:1. Even morepreferred, the hydrophilic compounds:biocompatible polymer ratio isbetween about 0.15:1 and 0.8:1; such as between about 0.15:1 and 0.7:1,for example between about 0.15:1 and 0.6:1, such as between about 0.15:1and 0.5:1, for example between about 0.15:1 and 0.5:1, such as between0.15:1 and 0.45:1. In a preferred embodiment, the hydrophiliccompounds:biocompatible polymer ratio is between about 0.2:1 and 0.8:1;such as between about 0.2:1 and 0.7:1, for example between about 0.2:1and 0.6:1, such as between about 0.2:1 and 0.5:1, for example 0.2:1 and0.45:1.

In one embodiment, the hydrophilic compounds:biocompatible polymer ratiois between about 0.3:1 and 0.8:1; such as between about 0.3:1 and 0.7:1,for example between about 0.3:1 and 0.6:1, such as between about 0.3:1and 0.5:1, for example between about 0.35:1 and 0.5:1, such as betweenabout 0.35:1 and 0.45:1.

In one embodiment the hydrophilic compound is not polyethylene glycol(PEG).

Further Compounds

The dry composition may further comprise one or more of the following:DMSO (dimethyl sulfoxide), 2-Methyl-2,4-pentanediol (MPD) and/or one ormore of the compounds mentioned in the table below.

Bulking agent Buffering agent Solubilising agent MiscellaneousSugars/Sugar Citric acid Complexing agent: Tonicifying agent: alcohols:Sodium citrate Ethylediamine tetra acetic Sodium chloride MannitolPotassium citrate acid (EDTA) Sucrose Lactose Tartaric acid Alphacyclodextrin Mannitol Sucrose Sodium phosphate Hydroxypropyl-β- DextroseTrehalose Tris base cyclodextrin (HP-β-CD) Sorbitol Tris HCl GlucoseTris acetate Raffinose Zinc chloride Sodium acetate Potassium acetateArginine Amino acids: pH adjusting agent: Surfactants: AntimicrobialArginine Hydrochloric acid polysorbate 80 agents: Glycine Sodiumhydroxide Benzalkonium Histidine Meglumine chloride benzyl alcoholphenol m-cresol methyl paraben ethyl paraben Polymer: Co-solvents:Collapse Dextran Tert-butyl alcohol temperature Polyethylene Iso-propylalcohol modifier: glycol Dichloromethane Dextran Ethanol Hydroxyethylstarch Acetone Ficoll Glycerol gelatin

In one embodiment, the dry composition comprises one or moreantimicrobial agents, such as one or more antibacterial agents.

In one embodiment, the dry composition comprises benzalkonium chloride.

In one embodiment, the dry composition does not comprise anantimicrobial agent.

In one embodiment, the dry composition further comprises an extrusionenhancer, i.e. a compound capable of facilitating extrusion of a pastefrom a syringe.

It has previously been shown that the provision of certain extrusionenhancers, such as albumin in an appropriate amount, enables the use ofhigher gelatine concentrations as it decreases the amount of forceneeded to extrude the gelatine paste composition from e.g. a syringe.The use of higher gelatine concentrations may in turn improve thehaemostatic properties of such products. It is necessary to provide theextrusion enhancers in appropriate amounts. The amounts are preferablyhigh enough so as to obtain the extrusion effect, i.e. to enable aflowable paste even for relatively high amounts of the biocompatiblepolymer, e.g. cross-linked gelatine, so that the haemostatic pastecomposition can be accurately applied by a surgeon using e.g. a syringecomprising an applicator tip; on the other hand, the amounts shall be aslow as to prevent negative functional properties of the haemostaticcomposition.

The extrusion enhancer is preferably albumin, especially human serumalbumin.

In the paste prior to drying, the extrusion enhancer, such as albumin,is preferably present in an amount of between about 0.1% to about 10%,such as between about 0.2% to about 8%, for example between about 0.3%to about 7%, preferably between about 0.5% to about 5%, more preferredbetween about 1% to about 4%.

In the dry composition, the extrusion enhancer, such as albumin, ispreferably present in an amount of between about 0.3% to about 30%, suchas between about 0.5% to about 25%, for example between about 1% toabout 20%, preferably between about 2% to about 15%.

In one embodiment, the extrusion enhancer is not present in the drycomposition, but is instead introduced into the paste composition duringreconstitution. For example the extrusion enhancer may be present in theaqueous medium used for reconstitution of the paste, thereby obtaining awet paste composition comprising the extrusion enhancer. Theconcentration of the extrusion enhancer in the reconstituted paste willbe the same as when the extrusion enhancer is added to the paste priorto drying.

In one embodiment, the reconstituted wet paste compositions according tothe present invention have a mean extrusion force (e.g. by employing thetest method described in example 1 of WO 2013/060770) of 40 N or below,preferably below 35 N, especially preferred below 30 N or even below 20N.

Another class of extrusion enhancers according to the present disclosureare phospholipids, such as phosphatidylcholine and -serine, or complexmixtures such as lecithins or soy bean oils.

Bioactive Agent

In one embodiment, the dry composition comprises one or more bioactiveagents, i.e. one or more bioactive agents are included in the pasteprior to drying. It is essential that the bioactive agent retains itsbioactivity throughout the process and that the agent has also retainedits biological function in the final reconstituted paste. Many bioactiveagents are unstable in solution, particularly enzymes and other proteinsthat may be degraded or otherwise lose their secondary structure whenwater is present.

In one embodiment the bioactive agent is thrombin.

In one embodiment the thrombin is human thrombin.

In one embodiment the thrombin is recombinant thrombin.

Conventionally, a thrombin solution is mixed with a dry or pre-wettedgelatine powder to make a haemostatic paste directly at the surgicalsite at the time of need of the haemostatic paste, e.g. by usingcommercially available haemostatic kits such as Floseal® and Surgiflo®.The thrombin solution must be made just prior to making the paste asthrombin in solution is very unstable and will self-degrade rapidly. Themaking of a thrombin solution at the surgical site is time consuming andinvolves a risk of making mistakes regarding the correct dilution andamount of thrombin.

The present disclosure allows for the addition of thrombin to the pasteprior to drying, thereby resulting in a dry haemostatic compositioncomprising thrombin, which upon reconstitution with a suitable aqueousmedium, will comprise a desired amount of thrombin without the need fortime-consuming and error-prone thrombin dilution steps and addition atthe surgical site. That thrombin may be included in the dry compositionof the present disclosure thus constitutes a clear advantage overconventional methods for making haemostatic pastes.

Thrombin may be included in a paste and dried by freeze-drying accordingto the present disclosure with essentially no loss of thrombin activitymeasured in the reconstituted paste.

Thrombin may be added to the paste of the present disclosure prior todrying in an amount sufficient to ensure effective haemostasis of thereconstituted dry composition. In one embodiment thrombin is added at aconcentration in the range of about 100 IU/ml paste to about 500 IU/mlpaste, such as about 150 IU/ml paste to about 450 IU/ml paste, forexample about 200 IU/ml paste to about 400 IU/ml paste, such as about250 IU/ml paste to about 350 IU/ml paste.

In one embodiment, thrombin is added to the paste prior to drying at aconcentration in the range of about 50 IU/g paste to about 5000 IU/gpaste, preferably between about 100 IU/g paste to about 1000 IU/g paste,such as between about 200 IU/g paste to about 800 IU/g paste. In suchembodiments, the dry composition will comprise thrombin.

In other embodiments, the dry composition does not comprise thrombin andthrombin may be added upon reconstitution of the dry composition byreconstituting the dry paste composition with a liquid comprisingthrombin.

The one or more bioactive agents can be e.g. thrombin or thrombin incombination with fibrinogen, or thrombin and fibrinogen in combinationwith Factor XIII, or thrombin and fibrinogen and Factor XIII incombination with tranexamic acid.

Thrombin is a “trypsin-like” serine protease protein that in humans isencoded by the F2 gene. Prothrombin (coagulation factor II) isproteolytically cleaved to form thrombin in the coagulation cascade,which ultimately results in the stemming of blood loss. Thrombin in turnacts as a serine protease that converts soluble fibrinogen intoinsoluble strands of fibrin, as well as catalyzing many othercoagulation-related reactions. In the blood coagulation pathway,thrombin acts to convert factor XI to XIa, VIII to VIIIa, V to Va, andfibrinogen to fibrin.

A preferred bioactive agent according to the invention is thrombin. Inone embodiment, the thrombin is added as prothrombin.

In one embodiment, the dry composition comprises one or more bioactiveagents that stimulate bone and/or tendon and/or tissue healing such asone or more growth factors selected from the group consisting of matrixmetalloproteinases (MMPs), insulin-like growth factor 1 (IGF-I),platelet-derived growth factor (PDGF), vascular endothelial growthfactor (VEGF), basic fibroblast growth factor (bFGF) and transforminggrowth factor beta (TGF-β).

In one embodiment, the dry composition comprises one or more BoneMorphogenetic Proteins (BMPs). Bone morphogenetic proteins (BMPs) are asubgroup of the TGF-β superfamily. Bone Morphogenetic Proteins (BMPs)are a group of growth factors also known as cytokines and asmetabologens. Originally discovered by their ability to induce theformation of bone and cartilage, BMPs are now considered to constitute agroup of pivotal morphogenetic signals, orchestrating tissuearchitecture throughout the body.

In one embodiment, the dry composition of the present disclosurecomprises one or more matrix metalloproteinases (MMPs). MMPs arezinc-dependent endopeptidases. MMPs have a very important role in thedegradation and remodeling of the extracellular matrix (ECM) during thehealing process after an injury. Certain MMPs including MMP-1, MMP-2,MMP-8, MMP-13, and MMP-14 have collagenase activity, meaning that,unlike many other enzymes, they are capable of degrading collagen Ifibrils.

These growth factors all have different roles during the healingprocess. IGF-1 increases collagen and proteoglycan production during thefirst stage of inflammation, and PDGF is also present during the earlystages after injury and promotes the synthesis of other growth factorsalong with the synthesis of DNA and the proliferation of cells. Thethree isoforms of TGF-β (TGF-β1, TGF-β2, TGF-β3) are known to play arole in wound healing and scar formation. VEGF is well known to promoteangiogenesis and to induce endothelial cell proliferation and migration.

In one embodiment, the dry composition of the present disclosurecomprises flakes or particles of extracelluar matrix (ECM). ECM is theextracellular part of animal tissue that usually provides structuralsupport to the animal cells in addition to performing various otherimportant functions. ECM has been shown to have very beneficial effectin healing as it facilitates functional tissue regeneration.

The variety of biological agents that can be used in conjunction withthe paste of the invention is vast. In general, biological agents whichmay be administered via compositions of the present disclosure include,without limitation, antiinfectives, such as antibiotics and antiviralagents; analgesics and analgesic combinations; antihelmintics;antiarthritics; anticonvulsants; antidepressants; antihistamines;antiinflammatory agents; antimigraine preparations; antineoplastics;antiparkinsonism drugs; antipsychotics; antipyretics, antispasmodics;anticholinergics; sympathomimetics; xanthine derivatives; cardiovascularpreparations including calcium channel blockers and beta-blockers suchas pindolol and antiarrhythmics; antihypertensives; diuretics;vasodilators, including general coronary, peripheral and cerebral;central nervous system stimulants; hormones, such as estradiol and othersteroids, including corticosteroids; immunosuppressives; musclerelaxants; parasympatholytics; psychostimulants; naturally derived orgenetically engineered proteins, polysaccharides, glycoproteins, orlipoproteins; oligonucleotides, antibodies, antigens, cholinergics,chemotherapeutics, radioactive agents, osteoinductive agents,cystostatics heparin neutralizers, procoagulants and haemostatic agents,such as prothrombin, thrombin, fibrinogen, fibrin, fibronectin,heparinase, Factor X/Xa, Factor VII/VIIa, Factor VIII/VIIIa, FactorIX/IXa, Factor XI/XIa, Factor XII/XIIa, Factor XIII/XIIIa, tissuefactor, batroxobin, ancrod, ecarin, von Willebrand Factor, collagen,elastin, albumin, gelatin, platelet surface glycoproteins, vasopressin,vasopressin analogs, epinephrine, selectin, procoagulant venom,plasminogen activator inhibitor, platelet activating agents andsynthetic peptides having haemostatic activity.

Making the Paste

According to the method of the invention, the biocompatible polymer inpowder form and the alkaline compound are mixed with a suitable amountof an aqueous medium to obtain a paste, which is subsequently dried.Alternatively, the biocompatible polymer in powder form is mixed with anacidic compound in the presence of a suitable amount of an aqueousmedium to obtain a paste and the paste is subsequently dried. The mixingis performed under conditions effective to provide a substantiallyhomogeneous paste composition and may be performed in any suitable wayknown to a person of skill, e.g. by mixing the contents manually or byusing an electrical mixing apparatus, such as a hand mixer, a kitchenmixer or an industrial mixer.

The powder particles of the biocompatible polymer are usuallysubstantially insoluble in the aqueous medium allowing for a paste toform. Cross-linking generally renders biocompatible polymers, such asgelatine, insoluble in water.

Mixing of the paste in the mixing vessel introduces a discontinuous gasphase substantially homogenously dispersed through the paste, i.e. themixed paste will comprise pockets or isolated bodies of gas, such asair.

In one embodiment, the paste is made by mixing an aqueous medium, a gasand an amount of powder particles in a mixing vessel under conditionsresulting in the formation of a paste having a discontinuous gas phasesubstantially homogenously dispersed through the paste. The gas may forexample be air, nitrogen, carbon dioxide, xenon, argon or mixturesthereof.

In a particular embodiment, the paste is prepared by the followingsteps:

-   -   introducing a volume of a liquid into a mixing vessel equipped        with a means for mixing said liquid,    -   introducing a volume of a gas into said volume of liquid while        said means for mixing is operating under conditions effective to        mix said liquid and said gas together to form a foam comprising        a discontinuous gas phase comprising said gas dispersed in a        continuous liquid phase comprising said liquid,    -   introducing into said foam an amount of powder particles of a        biocompatible polymer suitable for use in hemostasis and which        is substantially insoluble in said liquid; and    -   mixing said foam and said powder particles together under        conditions effective to form a substantially homogenous paste        composition comprising said discontinuous gas phase and said        particles substantially homogenously dispersed throughout said        liquid phase, thereby forming a paste composition.

In one embodiment, the substantially homogenous paste compositioncomprises a continuous liquid phase, i.e. a liquid phase which can bereleased when applying force to the paste when the paste is contained inan enclosed space.

In one embodiment, the powder particles comprise pores and channels of asize sufficient to hold water by capillary forces. When a paste is madeusing such particles, water can be released from the paste uponapplication of force to the paste when the paste is contained in aconfined space.

The obtained paste is then transferred into a container suitable forvacuum expansion, freezing and drying of the paste. Preferably, thecontainer into which the paste is transferred is also suitable forreconstituting and applying the reconstituted paste composition, e.g. toa site requiring hemostasis.

The mixing of the paste can generally be performed at room temperature(20-25° C.). However, if thrombin or other sensitive agents, such asother enzymes are included in the paste, it is advisable to perform themixing of the paste at chilled temperatures and/or within a short timeperiod to avoid or decrease the proteolytic activity of thrombin, as itis well-known that thrombin is liable to self-degradation when wet.Hence, when thrombin or other sensitive bioactive agents are to beincluded in the paste, the mixing of the paste is usually performed attemperatures below room temperature, such as at about 2° C. to about 25°C., for example at about 2° C. to about 15° C., such as about 2° C. toabout 10° C., preferably at about 4° C.

Another or an additional way of preserving the thrombin bioactivity inthe paste is to keep the time that thrombin is in a wet state, i.e. themixing time, at a minimum. Hence, when thrombin or other proteolyticenzymes are to be included in the paste, the mixing of the paste isusually performed within about 5 minutes to about 10 hours, such asabout 5 minutes to about 5 hours, for example about 5 minutes to about 2hours, preferably about 5 minutes to about 1 hour, such as within about5 minutes to about 30 minutes.

It is not essential to perform the mixing of the paste at lowtemperatures to avoid loss of thrombin activity as no detectabledecrease in thrombin activity was discovered when mixing of the pastewas performed at ambient temperatures (Example 2).

The density of the wet paste is usually in the range of about 0.5 g/mlto about 1 g/ml, such as between about 0.6 g/ml to about 0.9 g/ml, forexample between about 0.7 g/ml to about 0.8 g/ml.

Containers

Any suitable container known to a person of skill may be used forpreparing the paste and holding the paste of the present disclosurewhile drying, such as vials, jars, tubes, trays, cartridges or syringes.

In one embodiment, the paste is prepared in one container in bulk, suchas in a large mixing bowl, and transferred/aliquoted into anothercontainer for drying, wherein said other container is selected from anapplicator, such as a syringe, a vial, a jar, a tube, a tray and acartridge. Preferably, the other container is a medical delivery devicesuitable for dispensing flowable haemostatic compositions to a patientin need thereof.

In one embodiment the container holding the paste composition duringdrying is an applicator, such as a syringe.

A “jar” according to the invention is a rigid, approximately cylindricalcontainer with a wide mouth opening. Jars may comprise a re-closableclosure unit/lid applied to the mouth of the jar.

The containers may be made from any suitable material such as plastic,glass, ceramic or metal, such as stainless steel.

Examples of suitable plastic materials include but are not limited topolyethylene, polypropylene, polystyrene, polyvinyl chloride, andpolytetrafluoroethylene (PTFE).

In one embodiment, the paste is filled into and dried within anapplicator suitable for dispensing flowable haemostatic compositions.

In one embodiment, the present disclosure relates to a containercomprising:

-   -   a) a product chamber comprising the dry composition according to        the present disclosure, and    -   b) a valve.

In one embodiment, the container of the present disclosure is a partialsyringe assembly comprising the dry composition as defined herein and avalve.

Preferably, the dry composition reconstitutes spontaneously to form aflowable paste upon addition of an aqueous medium to the dry compositionbeing present in the container.

In one embodiment, the pressure within the product chamber is less thanthe pressure outside the product chamber.

In one embodiment, the container comprises a bypass allowing for gaseouscommunication between the product chamber and the outside of thecontainer during drying.

Gaseous communication during vacuum expansion and drying can also occurthrough the valve in embodiments of the present disclosure involvingvacuum expansion of the paste when the container does not comprise abypass.

The dry composition of the present disclosure may be prepared in variousshapes, forms and sizes depending on the shape of the container used.They may be e.g. in the form of plugs, disks, rods, tubes, conicalcylinders, spheres, half spheres, tablets, pellets, granules or sheets.

In one embodiment, the container is a medical delivery device.

Medical Delivery Device

In one embodiment, the paste is filled into and dried within a medicaldelivery device suitable for dispensing flowable haemostaticcompositions, such as a syringe. The transfer takes place before dryingof the paste. In embodiments of the present disclosure involving vacuumexpansion of the paste prior to drying, the transfer takes place beforevacuum expansion.

In one embodiment, the medical delivery device is a single-use syringecomprising a valve. In one embodiment, the syringe comprises alyophilisation bypass channel being a gaseous communication between theproduct chamber of the syringe and the outside of the container, i.e.the external environment. The bypass may be in an open state allowingfor gaseous communication between the product chamber and the outside,and in a closed state. The bypass may be located anywhere allowing forgaseous communication between the product chamber and the externalenvironment e.g. in the syringe body or in the plunger as shown in FIG.5. If the syringe comprises a bypass in the syringe body (FIG. 5,concept 2), the syringe may be fitted with a standard plunger.

One embodiment of the present disclosure relates to a syringe forretaining a freeze-dried paste, such as the presently disclosed drycomposition, in a vacuum comprising a barrel comprising a vacuum chamberfor containing the paste having an open proximal end and a distal endhaving a first fluid opening, a connector portion having a second fluidopening and adapted for connection to a liquid receptacle, and apressure chamber connecting the connector portion and the distal end ofthe vacuum chamber, a pressure valve located in the pressure chamber andadapted to seal the first and/or second fluid openings in a firstposition and form a fluid passageway between the first and second fluidopenings in a second position, a plunger configured to be axiallydisplaced in the vacuum chamber through the open proximal end, andoptionally one or more vacuum bypass channels. The syringe is preferablya single-use disposable syringe.

When freeze-drying the paste the vacuum that can be created in thevacuum chamber can be used to expand the paste prior to drying. And byretaining the dry paste in a vacuum in the vacuum chamber of thesyringe, i.e. at a pressure level lower than the surrounding ambientpressure, addition of liquid upon preparation and use of the paste iseased, because the liquid is sucked into the vacuum chamber due to thereduced pressure in the vacuum chamber.

The barrel may be provided with a flange at the proximal end of thevacuum chamber in order to ease handling of the syringe when operatingthe plunger. Furthermore, he inside volume of the vacuum chamber and/orthe pressure chamber may advantageously be cylindrical.

The connector portion may be a connector portion of a standard type,such as a Luer lock or Luer slip connector, preferably a male Luer lockor Luer slip connector. The connector portion may be provided with athreaded portion for secure connection with matching connector. Thisthreaded portion may be provided at the inside of the connector portionas illustrated in FIGS. 18a, 18b, 20a and 20 b.

In one embodiment of the presently disclosed syringe the pressure valvecomprises a groove. This groove may form the fluid passageway in thesecond position of the pressure valve. One example is illustrated inFIGS. 18a and 18b . As also illustrated in FIGS. 18a and 18b thepressure valve 5 may comprise two cylindrical sections axially dividedby a groove 12, and wherein the void formed by the groove 12 forms thefluid passageway in the second position of the pressure valve 5. In thisconfiguration the pressure valve may be rotation symmetric along thelongitudinal axis of the pressure valve as seen from FIG. 18, i.e. thepressure valve may be rotated inside the pressure chamber withoutinterfering with the function of the pressure valve, i.e. in the firstposition of the pressure valve the vacuum chamber is sealed independentof the rotational position of the pressure valve, and in the secondposition of the pressure valve a fluid connection is formed between thevacuum chamber and the connector portion independent of the rotationalposition of the pressure valve.

The pressure valve may be provided in a rubbery material and/or with arubbery surface to provide for the sealing of the first and second fluidopenings in the first position of the pressure valve.

The pressure chamber is preferably located between the vacuum chamberand the second fluid opening. Furthermore, the pressure valve ispreferably located in the pressure chamber and adapted to seal the firstand second fluid openings in a first position in the pressure chamberand form/create a fluid passageway between the first and second fluidopenings in a second position in the pressure chamber, e.g. the pressurevalve is preferably located in the pressure chamber, e.g. inside thepressure chamber, in both the first and second positions. I.e.preferably the pressure valve stays inside the pressure chamber duringcontrol of the fluid passage between the first and second fluidopenings.

In one embodiment of the presently disclosed syringe the pressurechamber comprises a proximal end abutting the distal end of the vacuumchamber and a distal end abutting a proximal end of the connectorportion. Further, the connector portion may comprise a proximal endabutting a distal end of the pressure chamber and a distal end adaptedfor connection to a liquid receptacle. The second fluid opening may forman elongated channel through the connector portion, e.g. as illustratedin FIGS. 18 and 20. As also seen from these figures the second fluidopening may comprise a proximal end abutting a distal end of thepressure chamber and a distal end for inlet and outlet of fluid. Hence,the pressure valve may be adapted to seal a distal end of the firstfluid opening and a proximal end of the second fluid opening in saidfirst position.

Thus, with the presently disclosed syringe the liquid for reconstitutionof a dry composition in the vacuum chamber to obtain a paste can beprovided from the distal end of the syringe, via the second fluidopening in the connector portion and through the pressure chamber andinto the vacuum chamber. Delivery of the reconstituted paste is alsoprovided through the distal end of the syringe. This solution ispossible because of the provision of the dedicated pressure chamber withthe pressure valve located between the vacuum chamber and the distalfluid opening, whereby it may be possible to control the blockage andopening of the fluid passageway between the first and second fluidopenings without removing the pressure valve from the pressure chamberand also without access to the second fluid opening. Thus, an externalliquid receptacle may be connected to the connector portion of thesyringe while the pressure valve is in the first position, i.e. thefluid passageway is blocked (sealed). Switching the pressure valve tothe second position opens the fluid passageway and liquid can pass fromthe liquid receptacle to the vacuum chamber of the syringe forreconstitution of the dry composition. The presently disclosed syringeis therefore safe, easy and quick to use when reconstituting a dry pastecomposition, such as a haemostatic paste.

In a further embodiment of the presently disclosed syringe the first andsecond positions of the pressure valve are radially displaced withrespect to the longitudinal axis of the syringe. Furthermore, thepressure valve may protrude from the pressure chamber in the firstposition of the pressure valve. And further, the pressure valve may beflush with the pressure chamber in the second position of the pressurevalve, e.g. fully incorporated in the pressure chamber. The pressurevalve may be provided with a valve flange at an end of the pressurevalve protruding from the pressure chamber. This valve flange mayprotrude from the pressure chamber in said first position, and the valveflange may be flush with the pressure chamber in said second position.The valve flange may then have the function as a stop flange for thepressure valve, i.e. the pressure valve may be configured such that thevalve flange abuts the pressure chamber in the second position of thepressure valve.

In yet another embodiment of the presently disclosed syringe the firstand second positions of the pressure valve are rotatably displaced, e.g.as illustrated in FIGS. 3-13, with the closed position in FIGS. 3-12 andthe open position in FIG. 13. As also exemplified in these figures thepressure valve may comprise a through-going channel forming the fluidpassageway in the second position of the pressure valve. Furthermore thepressure valve may comprise a cylindrical section with a through-goingradial channel forming the fluid passageway in the second position ofthe pressure valve.

In a further embodiment the pressure valve and the pressure chamber areconfigured such that the second position of the pressure valve is alocked position. The pressure valve may be axially and/or rotatablylocked in this locked position. This may help to ensure that once thepressure valve has been moved to the second position, it stays there,thereby ensuring that paste can be expelled from the syringe whenneeded. The pressure valve and the pressure chamber may further beconfigured such the first position is a partly locked position, e.g. thepressure valve cannot be removed from/out of the pressure chamber butcan only be moved into the second position. This may help to ensure thatthe vacuum is retained inside the vacuum chamber.

In a further embodiment of the presently disclosed syringe the pressurevalve comprises an aperture, and this aperture preferably forms at leasta part of the fluid passageway in the second position of the pressurevalve. I.e. preferably this aperture extends transversally through thepressure valve such that the aperture extends in the longitudinaldirection of the barrel when inserted in the pressure chamber.

In a further embodiment the pressure valve and the pressure chamber areconfigured such that the pressure valve is radially limited in saidfirst position, such as radially limited outwards with respect to thelongitudinal axis of the barrel. This radial limitation may be providedby means of one or more protrusions on the pressure valve and/or insidethe pressure chamber. E.g. the pressure valve comprises one or moreprotrusions, preferably extending sideways, such as radial to the fluidpassageway. The limitation may also be provided by means of a narrowingof an inner side wall of the pressure chamber and this narrowing may beadapted to limit a radial displacement of the pressure valve in thefirst position, e.g. this narrowing may be adapted to match one or moreprotrusions of the pressure valve, such that this or these protrusionsabuts the narrowing in the first position of the pressure valve. Anarrowing may be provided by means of one or more “shoulders” of aninner side wall of the pressure chamber, as exemplary illustrated inFIGS. 19c and 19 d.

In a further embodiment the pressure valve protrudes transversely and/orradially from the pressure chamber in said first position and whereinthe pressure valve is flush with or totally submerged into the pressurechamber in said second position. The pressure valve may be provided witha top surface, wherein said top surface may be flush with a top surfaceof the pressure chamber in said first position. These top surfaces maybe rounded and/or matched to each other as illustrated in FIGS. 19 and20.

The pressure valve and the pressure chamber may be configured such thatthe pressure valve can be inserted from one side of the pressurechamber, such as through only one side of the pressure chamber, e.g.through an opening of the pressure chamber, e.g. a bottom opening of thepressure chamber where a top opening of the pressure chamber may bewhere through the pressure valve extends when in the first position.

The presently disclosed syringe is preferably configured such that apaste composition may be freeze-dried inside the vacuum chamber. The oneor more vacuum bypass channels may be configured to provide a fluid,such as a gaseous, communication between the vacuum chamber and thesurroundings/the ambient atmosphere, i.e. the vacuum bypass channel(s)may function as the lyophilisation bypass channel as described herein.In one embodiment the syringe is configured such that the plungersealably engages the vacuum chamber in at least a first axial positionof the plunger inside the vacuum chamber, and such that fluidcommunication is established across the plunger in at least a secondaxial position of the plunger inside the vacuum chamber via said one ormore vacuum bypass channels. I.e. a vacuum can be established and thecomposition can be freeze-dried in the second position of the plunger,whereas the vacuum in the vacuum chamber can be retained in the firstposition of the plunger. However, alternatively said one or more vacuumbypass channels are configured such that a fluid communication can beprovided directly between the vacuum chamber and the ambient atmosphereindependent of the position of the plunger, e.g. via a (second) pressurevalve located directly at the vacuum chamber. Alternatively said one ormore vacuum bypass channels may be formed in the plunger.

Hence, the one or more vacuum bypass channels may be configured to breakthe sealing between the vacuum chamber and the plunger at a predefinedaxial position of the plunger inside the vacuum chamber. Furthermore,said one or more vacuum bypass channels may be formed in the vacuumchamber. E.g. said one or more vacuum bypass channels may be one or morelongitudinal grooves formed in the inner surface, e.g. at the proximalend of the vacuum chamber.

In one embodiment of the presently disclosed syringe the barrel isformed in a single piece of material. The barrel may advantageously besuitable and/or adapted for manufacture by means of single cycleinjection moulding, i.e. the barrel may advantageously be manufacturedby means of single cycle injection moulding. I.e. the vacuum chamber,the pressure chamber and the connector portion may be integrated and/orincorporated to form a single element, e.g. as illustrated in FIGS.16-18. This may help to ensure that a vacuum can be established andretained inside the vacuum chamber.

However, alternatively the vacuum chamber, the pressure chamber and theconnector portion may be formed as separate elements and configured tobe assembled during manufacture of the syringe.

Further, the pressure chamber and the connector portion may be formed asone element and configured to be assembled with the vacuum chamberduring manufacture of the syringe. Alternatively the vacuum chamber andthe pressure chamber may be formed as one element and configured to beassembled with the connector portion during manufacture of the syringe.

A barrel 1, 1′ of the presently disclosed syringe is exemplified inFIGS. 16-18. The barrel 1 in FIG. 16a is provided with a vacuum chamber,a pressure chamber 3, a connector portion 4 and a flange 8 formed in asingle piece and suitable for manufacture by single cycle injectionmoulding. The pressure valve 5 inserted in the pressure chamber 3 isprovided with a valve flange 6. In FIG. 16a the pressure valve islocated in a first position whereas in FIG. 16b the pressure valve hasbeen displaced to a second position. This is more clearly seen in FIGS.16c (first position of pressure valve) and 16 d (second position). Inthe second position of the pressure valve 5 the valve flange 6 abuts thepressure chamber 3.

The cut-through illustrations in FIGS. 18a and 18b more clearly showsthe configuration of the pressure valve 5. In the first position in FIG.18a the pressure valve blocks the fluid communication between the outlet11 of the internal volume 2′ of vacuum chamber 2 and the outlet 7 of theconnector portion 4. In the second position of the pressure valve 5 inFIG. 18b a fluid communication is provided (as illustrated by the dottedline/arrow) between the surroundings and the internal volume 2′ of thevacuum chamber 2 via the pressure chamber 3 and the outlet 7 of theconnector portion 4, i.e. liquid can enter the vacuum chamber 2′ to mixwith a dry composition, e.g. to form a wet paste that subsequently canbe controllably released via the outlet 7 by operating a plunger (notshown) arranged in the barrel 1, 1′. The barrel 1′ in FIG. 17a does nothave a flange.

As seen from FIG. 18 the pressure valve 5 is formed like a cylinder witha circumferential groove 12 that forms the fluid opening in the secondposition of the pressure valve. I.e. the pressure valve 5 is formed liketwo hollow cylinders that are attached to each other by means of thecentrally located rod 13. Even though the rod 13 is located centrally inthe fluid passageway, liquid that enters the vacuum chamber 2 via theoutlet 7, and paste that is released from the barrel 1, 1′ through theoutlet 7 can easily pass the rod 13. The pressure valve 5 as illustratedin FIG. 18 is rotation symmetric.

The connector portion 4 is provided with an internal thread 10, mostclearly seen in FIG. 18. This may help to provide a secure, tight andtamper-free connection with an external liquid container (having aconnector portion with a matching thread) prior to suction of liquidinto the vacuum chamber when the (wet) paste is to be formed.

Vacuum bypass channels 9 are provided in FIGS. 16-18 as longitudinallyextending grooves in the proximal end of the vacuum chamber 2. When theplunger (not shown) is arranged in the barrel 1, 1′ below these vacuumchannels the plunger sealably engages the vacuum chamber. However, whenthe distal part of the plunger is flush with the bypass vacuum channels9, this sealing is not tight, because a fluid, and in particular air,connection is established between the vacuum chamber 2′ and thesurrounding atmosphere across the plunger via the vacuum bypass channels9. I.e. during free-drying of paste inside the vacuum chamber 2′ suctionapplied at the proximal end of the barrel can establish a vacuum insidethe pressure chamber 2′ and thereby expand the dry paste. At the end ofthe freeze-drying and expansion process, the plunger can be displaced toa position below the vacuum bypass channels, thereby sealably engagingthe vacuum chamber 2 and subsequently retaining the freeze-dried pastein a vacuum.

Another exemplary barrel 1″ of the presently disclosed syringe isexemplified in FIG. 20 having another embodiment of the pressure valve5′ and the pressure chamber 3′ as illustrated in greater detail in FIG.19, with FIG. 19a showing a close-up of the pressure valve alone. Thispressure valve 5′ is slim and provided in a substantially rectangularshape. An aperture 17 forms the fluid passageway in the second positionof pressure valve inside the pressure chamber 3′. The outside shape ofthe pressure valve 5′ matches the inside shape of the pressure chamber3′. FIG. 19b shows the pressure valve 5′ inside the pressure chamber 3′in the first position of the pressure valve 5′, where the fluidpassageway is blocked and a vacuum can be retained inside the vacuumchamber 2. In FIG. 19b the pressure valve 5′ is seen to protrude upwardsfrom the pressure chamber 3′, i.e. it protrudes radially from thepressure chamber 3′ with respect to the longitudinal axis of the barrel2. In FIGS. 19c and 19d the pressure chamber 3′ has been cut-throughsuch that the configuration of the pressure valve 5′ inside the pressurechamber 3′ can be seen. In FIG. 19c the pressure valve 5′ is in thefirst position, i.e. extending radially from the pressure chamber 3′.The pressure valve 5′ and the pressure chamber 3′ are configured suchthat the pressure valve is radially limited in this first position bymeans of protrusions 14 on the pressure valve 5′ that abuts a narrowing15 of the inner side wall of the pressure chamber 3′, i.e. the pressurevalve 5′ cannot extend further outwards when in the first position. Thishelps to ensure that the pressure valve 5′ is not accidentally removedfrom the pressure chamber 3′ thereby possibly breaking a vacuum sealinginside the vacuum chamber 2. In FIG. 19d the pressure valve 5′ is in thesecond position. The pressure valve 5′ is now completely submerged inthe pressure chamber 3′. The rounded top surface of the pressure valve5′ matches a corresponding rounded top surface of the pressure chamber3′ such that the upper surfaces of the pressure valve 5′ and thepressure chamber 3′ are flush with each other.

FIGS. 20a-b show cut-through side view illustrations of the pressurevalve 5′ inside the pressure chamber 3′ with the first position of thepressure valve in FIG. 20a and the second position in FIG. 20b . As seenin FIG. 20a the fluid passageway 7 is blocked by the pressure valve 5′,whereas in FIG. 20b the aperture 17 of the pressure valve 5′ establishesa fluid connection as indicated by the stippled horizontal arrow in FIG.20b . FIG. 20b also illustrates how the pressure valve 5′ does notprotrude from the pressure chamber 3′ in this second position. Thishelps to ensure that once the fluid passageway has been established bythe pressure valve 5′ in the second position, the position of thepressure valve 5′ is not easily changed because it is submerged insidethe pressure chamber 3′.

A stippled arrow in FIG. 20a indicates the opening 16 where through thepressure valve 5′ can be inserted into the pressure chamber 3′. Thebarrel 1″ is also suitable for single cycle injection molding. Aftermanufacture the pressure valve 5′ can be inserted through the opening16. The pressure valve 5′ in itself is also suitable for single cycleinjection molding. The three top holes 18 indicated in FIGS. 19a and 20care provided to make the pressure valve 5′ suitable for injectionmolding.

Haemostatic Sheet

In one embodiment the dry composition is in the form of a sheet, i.e. asubstantially flat composition.

A dry composition in the form of a sheet may be obtained by spreadingthe paste of the invention thinly and evenly on a surface and drying ofthe paste to obtain a substantially flat dry sheet composition. A drycomposition in the form of a sheet will upon contact with a liquidreconstitute spontaneously to form a paste. Thus, a dry composition inthe form of a sheet has the advantages of both traditionally usedsurgical sponges in that it can cover relatively large areas and theadvantage of a paste in that it conforms easily to uneven surfaces uponwetting.

The dry composition in the form of a sheet is soft and flexible.

In one embodiment the invention relates to a dry composition in the formof a sheet for use in haemostasis and/or wound healing.

In one embodiment, the sheet is not pre-wetted before use, i.e. beforeapplication to a wound. In this case, the sheet will reconstitute insitu on the bleeding wound upon contact with blood, wound exudate,and/or other bodily fluids.

The height of the dry sheet composition is in one embodiment betweenabout 0.5 mm and about 10 mm, preferably between about 1 mm and 5 mm,more preferred between about 1 mm and 3 mm, such as about 2 mm.

The size (width and depth) of the dry sheet composition depends on theintended use of the sheet and can be selected by the skilled person. Thedry sheet material may e.g. be rectangular, square or circular. Forexample, the dry sheet composition may e.g. be in the form of arectangle of approximately 5 cm×10 cm, 2 cm×6 cm, 6 cm×8 cm or 8 cm×12cm.

The dry sheet composition can be cut into any desired shape prior touse.

Vacuum Expansion

In one embodiment of the present disclosure, the paste is expanded bysubjecting the paste to a reduced pressure (a low vacuum) before thepaste is dried. Vacuum expansion results in an increase in the totalvolume of the paste by expansion of entrapped air or another gas withininterstitial pores or compartments of the wet paste. Vacuum expansion ofa paste prior to drying significantly decreases the reconstitution timeof the dried paste. For example, a vacuum expanded, dry gelatine pastecomposition being present in a medical delivery device will reconstitutewithin seconds to a ready-to-use paste suitable for direct delivery to apatient without any mechanical mixing required upon addition of anamount of an aqueous medium to the medical delivery device having thedry gelatine paste composition disposed therein.

Vacuum expansion expands entrapped air pockets within the paste and suchexpanded air pockets are retained in the dry composition. The presenceof larger air pockets in the dry composition presumably enables thewetting of the dry composition due to a larger contact surface areabetween the dry composition and the liquid. It also facilitatesunhindered distribution of the liquid into the dry composition due tothe formed channels.

The inventors have also discovered that the volume of a paste aliquot isgenerally higher in samples being aliquoted first as opposed to lastfrom a single batch of paste. This is thought to be due to a partialcollapse of the paste occurring over time causing variations in pastedensity before drying. Such variations in density can lead toundesirable variations in the reconstitution time. Vacuum expansion ofthe paste prior to drying is able to reduce or even eliminate such“intra-batch” variations in paste density and thus lead to consistentlyfast reconstitution of the dried pastes. Thus, vacuum expansion providesa higher degree of reproducibility with regards to the reconstitutiontime.

The pressure of the vacuum is selected so that the paste expands to asufficient degree without collapsing. Thus, the pressure must not be toolow, which will result in the paste collapsing. Vacuum expansion of thepaste may e.g. be performed in a freeze-dryer.

Vacuum expansion of the paste is a result of one of the universal lawsof physics: the ideal gas law, which governs that the volume of a gaswill increase upon a decrease in pressure. The ideal gas law equationis:

PV=nRT

where P is the pressure of the gas, V is the volume of the gas, n is theamount of substance of gas (in moles), T is the temperature of the gasand R is the ideal, or universal, gas constant.

Subjecting a wet paste to a sub-atmospheric pressure results in anexpansion of the air or other gas within the interstitial spaces (pores)of the paste, which in turn leads to an increase in the total volume ofthe paste and a decrease in the density of the paste. After drying ofthe paste composition to achieve a dry paste composition, the increasedpore size results in increased permeability and wettability and thus anincreased reconstitution rate of the dry composition. Thus, in oneembodiment, the present disclosure relates to a method for adaptingpaste volume by adjusting paste density by subjecting a wet paste to areduced pressure.

In one embodiment the density of the paste is decreased by at least afactor 0.95 as a result of the vacuum expansion, such as at least afactor 0.90, for example at least a factor 0.85, such as at least afactor 0.80, for example at least a factor 0.75, such as at least afactor 0.70, for example at least a factor 0.65, such as at least afactor 0.60, for example at least a factor 0.55, such as at least afactor 0.50 as a result of the vacuum expansion. Preferably, the densityof the paste is decreased by at least a factor 0.8 as a result of thevacuum expansion.

In one embodiment the density of the paste is decreased by about afactor 0.75 as a result of the vacuum expansion.

Prior to vacuum expansion of the paste, the density of the wet paste maye.g. be in the range of about 0.5 g/ml to about 1 g/ml, such as betweenabout 0.6 g/ml to about 0.9 g/ml, for example between about 0.7 g/ml toabout 0.8 g/ml.

For example, the density of a gelatine paste prior to expansion isusually within the range of about 0.60 g/ml to about 0.80 g/ml, such asabout 0.65 g/ml to about 0.75 g/ml, such as about 0.7 g/ml.

The density of the wet paste after vacuum expansion is less than thedensity of the wet paste before vacuum expansion. For example, thedensity of the wet paste after vacuum expansion may e.g. be in the rangeof about 0.1 g/ml to about 0.8 g/ml, more preferred between about 0.2g/ml to about 0.7 g/ml, for example about 0.2 g/ml to about 0.6 g/ml,such as about 0.2 g/ml to about 0.5 g/ml.

For example, the density of a gelatine paste after expansion is usuallywithin the range of about 0.2 g/ml to about 0.6 g/ml, more preferredbetween about 0.3 g/ml to about 0.6 g/ml, such as between about 0.4 g/mlto about 0.5 g/ml.

The volume of the paste, by subjecting the paste to a reduced pressure,is approximately increased by at least about a factor 1.05, such as atleast a factor 1.1, for example at least a factor 1.2, such as at leasta factor 1.3, for example at least a factor 1.4, such as at least afactor 1.5, for example at least a factor 1.6, such as at least a factor1.7, for example at least a factor 1.8, such as at least a factor 1.9,for example at least a factor 2.0.

In one embodiment, the volume of the paste is increased by from about afactor 1.05 to about a factor 2.0, such as about a factor 1.1 to about afactor 1.8, for example about a factor 1.2 to about a factor 1.6 as aresult of the vacuum expansion of the wet paste.

After drying, the density of the dried paste composition is furtherdecreased due to removal of the water. After drying of the vacuumexpanded wet paste, the density of the dry paste composition is thususually within the range of about 0.1 mg/ml to about 100 mg/ml, morepreferred between about 1 mg/ml to about 50 mg/ml, such as between about5 mg/ml to about 40 mg/ml.

For example, a dry vacuum expanded composition comprising gelatineprepared by the method of the present disclosure usually has a densityof between about 1 mg/ml to about 40 mg/ml, such as between about 5mg/ml to about 35 mg/ml, for example between about 10 mg/ml to about 35mg/ml.

In one embodiment, the density of the vacuum expanded dry composition iswithin the range of about 1 mg/ml to about 40 mg/ml, more preferredbetween about 5 mg/ml to about 40 mg/ml, such as between about 5 mg/mlto about 38 mg/ml, for example between about 5 mg/ml to about 36 mg/ml,such as between about 5 mg/ml to about 34 mg/ml, for example betweenabout 5 mg/ml to about 32 mg/ml, such as between about 5 mg/ml to about30 mg/ml, for example between about 5 mg/ml to about 28 mg/ml, such asbetween about 5 mg/ml to about 26 mg/ml, for example between about 5mg/ml to about 24 mg/ml, such as between about 5 mg/ml to about 22mg/ml, for example between about 5 mg/ml to about 20 mg/ml.

In one embodiment, the paste is subjected to a reduced pressure of atleast 10 mbar less than ambient pressure, for example at least 50 mbarless than ambient pressure, such as at least 100 mbar less than ambientpressure, for example at least 150 mbar less than ambient pressure, suchas at least 200 mbar less than ambient pressure, for example at least250 mbar less than ambient pressure, such as at least 300 mbar less thanambient pressure, for example at least 350 mbar less than ambientpressure, such as at least 400 mbar less than ambient pressure, forexample at least 450 mbar less ambient pressure, such as at least 500mbar less than ambient pressure, for example at least 550 mbar lessambient pressure, such as at least 600 mbar less than ambient pressure,for example at least 650 mbar less ambient pressure, such as at least700 mbar less than ambient pressure, for example at least 750 mbar lessthan ambient pressure, such as at least 800 mbar less than ambientpressure, for example at least 850 mbar less than ambient pressure, suchas at least 900 mbar less ambient pressure.

The pressure of the vacuum is preferably selected so that the pressureis at least 50 mbar less than ambient pressure but no more than 900 mbarless than ambient, such as at least 100 mbar less than ambient pressurebut no more than 800 mbar less than ambient pressure.

The pressure of the vacuum is preferably selected so that the pressureis no more than 1000 mbar less than ambient pressure, such as no morethan 900 mbar less than ambient pressure, for example no more than 800mbar less than ambient pressure, such as no more than 700 mbar less thanambient pressure, for example no more than 600 mbar less than ambientpressure, such as no more than 500 mbar less than ambient pressure.

In one embodiment, the pressure of the vacuum is between less than 1000mbar and 100 mbar, such as between 950 mbar and 100 mbar, for examplebetween 900 mbar and 100 mbar, such as between 850 mbar and 100 mbar,for example between 800 mbar and 100 mbar, such as between 750 mbar and100 mbar, for example between 700 mbar and 100 mbar, such as between 650mbar and 100 mbar, for example between 600 mbar and 100 mbar, such asbetween 550 mbar and 100 mbar, for example between 500 mbar and 100mbar, such as between 450 mbar and 100 mbar, for example between 400mbar and 100 mbar, such as between 350 mbar and 100 mbar, for examplebetween 300 mbar and 100 mbar, such as between 250 mbar and 100 mbar,for example between 200 mbar and 100 mbar.

In one embodiment, the pressure of the vacuum is between less than 1000mbar and 200 mbar, such as between 1000 mbar and 250 mbar, for examplebetween 1000 mbar and 300 mbar, such as between 1000 mbar and 350 mbar,for example between 1000 mbar and 400 mbar, such as between 1000 mbarand 450 mbar, for example between 1000 mbar and 500 mbar, such asbetween 1000 mbar and 550 mbar, for example between 1000 mbar and 600mbar, such as between 1000 mbar and 650 mbar, for example between 1000mbar and 700 mbar, such as between 1000 mbar and 750 mbar, for examplebetween 1000 mbar and 800 mbar, such as between 1000 mbar and 850 mbar,for example between 1000 mbar and 900 mbar, such as between 1000 mbarand 950 mbar.

In a preferred embodiment, the pressure of the vacuum is between about900 mbar and 500 mbar.

The expansion rate depends on the vacuum pump and the size of the vacuumchamber, i.e. how fast pressure in the chamber can be decreased to thedesired level. The low vacuum levels according to the present disclosureare achieved almost instantaneously, thus expansion of the paste occursessentially instantaneously after starting the vacuum pump.

Vacuum expansion is usually performed at a temperature above thefreezing point of the paste. In one embodiment, vacuum expansion isperformed at ambient temperature or at temperatures below ambienttemperature, such as at temperatures of about 0° C. to about 25° C.,such as at about 2° C. to about 20° C., for example about 2° C. to about15° C., such as at about 2° C. to about 10° C., such as about 4° C. toabout 20° C., for example about 4° C. to about 15° C., such as at about4° C. to about 10° C. When the paste comprises sensitive bioactiveagents, such as thrombin, vacuum expansion is preferably performed attemperatures below ambient temperatures.

When the paste has been expanded to a desired degree, the paste isfrozen by subjecting the paste to a temperature below the freezing pointof the paste and/or the glass transition temperature of the paste for aperiod of time sufficient for the paste to freeze. Freezing occurswithout releasing the vacuum and freezing of the paste thus locks theexpanded paste structure in place. Thus, further changes in pressurehereafter will not affect the volume of the frozen paste. The freezingstep is preferably performed in a freeze-dryer.

The freezing point of the paste and/or the glass transition temperatureof the paste can be determined by the skilled person. The desiredtemperature of the frozen paste is approximately 5° C. less than thelowest of the freezing point of the paste and the glass transitiontemperature. E.g. if the freezing point of a paste is −35° C., the pasteshould be cooled to about −40° C.

Drying the Paste

According to the presently disclosed method, the paste is dried toobtain the dry composition. The paste may be dried by any suitablemethods known to a person of skill.

In a preferred embodiment, the paste is freeze-dried. Any suitablefreeze-drying technique and equipment known to the person of skill maybe used.

When freeze-drying is used to prepare the dry composition, expansion,freezing and drying can advantageously be performed as a continuousprocess in a single apparatus.

A further advantage of freeze-drying is that it allows for retention ofa vacuum inside the container holding the dry composition, which plays arole in the reconstitution of the dry composition.

Freeze-drying (also known as lyophilisation and cryodesiccation) is adehydration process typically used to preserve a perishable material ormake the material more convenient for transport. Freeze-drying works byfreezing the material and then reducing the surrounding pressure toallow the frozen water in the material to sublimate directly from thesolid phase to the gas phase.

There are essentially three categories of freeze-dryers: the manifoldfreeze-dryer, the rotary freeze-dryer and the tray style freeze-dryer.Two components are common to all types of freeze-dryers: a vacuum pumpto reduce the ambient gas pressure in a vessel containing the substanceto be dried and a condenser to remove the moisture by condensation on asurface cooled to −40 to −80° C. The manifold, rotary and tray typefreeze-dryers differ in the method by which the dried substance isinterfaced with a condenser. In manifold freeze-dryers a short usuallycircular tube is used to connect multiple containers with the driedproduct to a condenser. The rotary and tray freeze-dryers have a singlelarge reservoir for the dried substance.

Rotary freeze-dryers are usually used for drying pellets, cubes andother pourable substances. The rotary dryers have a cylindricalreservoir that is rotated during drying to achieve a more uniform dryingthroughout the substance. Tray style freeze-dryers usually haverectangular reservoir with shelves on which products, such aspharmaceutical solutions and tissue extracts, can be placed in trays,vials and other containers.

Manifold freeze-dryers are usually used in a laboratory setting whendrying liquid substances in small containers and when the product willbe used in a short period of time. A manifold dryer will dry the productto less than 5% moisture content. Without heat, only primary drying(removal of the unbound water) can be achieved. A heater must be addedfor secondary drying, which will remove the bound water and will producea lower moisture content.

Tray style freeze-dryers are typically larger than the manifold dryersand are more sophisticated. Tray style freeze-dryers are used to dry avariety of materials. A tray freeze-dryer is used to produce the driestproduct for long-term storage. A tray freeze-dryer allows the product tobe frozen in place and performs both primary (unbound water removal) andsecondary (bound water removal) freeze-drying, thus producing the dryestpossible end-product. Tray freeze-dryers can dry products in bulk or invials or other containers. When drying in vials, the freeze-drier issupplied with a stoppering mechanism that allows a stopper to be pressedinto place, sealing the vial before it is exposed to the atmosphere.This is used for long-term storage, such as vaccines.

Improved freeze drying techniques are being developed to extend therange of products that can be freeze dried, to improve the quality ofthe product, and to produce the product faster with less labor.

Ever since the 1930s, industrial freeze drying has been dependent on asingle type of equipment: the tray freeze drier. In 2005 a quicker andless-labor intensive freeze drying method was developed for bulkmaterials. This freeze drying process proved to be able to producefree-flowing powder from a single vessel. Known as [Active FreezeDrying] AFD technology, the new process used continuous motion toimprove mass transfer and hence cutting processing time, while alsoeliminating the need to transfer to and from drying trays and downstreamsize reduction devices.

There are four stages in the complete freeze-drying process:pretreatment, freezing, primary drying, and secondary drying.

Pretreatment includes any method of treating the product prior tofreezing. This may include concentrating the product, formulationrevision (i.e., addition of components to increase stability and/orimprove processing), decreasing a high vapor pressure solvent orincreasing the surface area. In many instances the decision to pretreata product is based on theoretical knowledge of freeze-drying and itsrequirements, or is demanded by cycle time or product qualityconsiderations. Methods of pretreatment include: Freeze concentration,Solution phase concentration, Formulation to Preserve ProductAppearance, Formulation to Stabilize Reactive Products, Formulation toIncrease the Surface Area, and Decreasing High Vapor Pressure Solvents.

In a lab, freezing is often done by placing the material in afreeze-drying flask and rotating the flask in a bath, called a shellfreezer, which is cooled by mechanical refrigeration, dry ice andmethanol, or liquid nitrogen. On a larger scale, freezing is usuallydone using a freeze-drying machine. In this step, it is important tocool the material below its triple point, the lowest temperature atwhich the solid and liquid phases of the material can coexist. Thisensures that sublimation rather than melting will occur in the followingsteps. Larger crystals are easier to freeze-dry. To produce largercrystals, the product should be frozen slowly or can be cycled up anddown in temperature. This cycling process is called annealing. In othercases it is better that the freezing is done rapidly, in order to lowerthe material to below its eutectic point quickly, thus avoiding theformation of ice crystals. Usually, the freezing temperatures arebetween −40° C. and −80° C. The freezing phase is the most critical inthe whole freeze-drying process, because the product can be spoiled ifbadly done.

Amorphous materials do not have a eutectic point, but they do have acritical point, below which the product must be maintained to preventmelt-back or collapse during primary and secondary drying.

During the primary drying phase, the pressure is lowered (to the rangeof a few millibars or less), and enough heat is supplied to the materialfor the water to sublime.

The amount of heat necessary can be calculated using the sublimatingmolecules' latent heat of sublimation. In this initial drying phase,about 95% of the water in the material is sublimated. This phase may beslow (can be several days in the industry), because, if too much heat isadded, the material's structure could be altered.

In this phase, pressure is controlled through the application of amedium vacuum. The vacuum speeds sublimation, making it useful as adeliberate drying process. Furthermore, a cold condenser chamber and/orcondenser plates provide a surface(s) for the water vapour tore-solidify on. This condenser plays no role in keeping the materialfrozen; rather, it prevents water vapor from reaching the vacuum pump,which could degrade the pump's performance. Condenser temperatures aretypically below −50° C.

It is important to note that, in this range of pressure, the heat isbrought mainly by conduction or radiation; the convection effect isnegligible, due to the low air density.

The vapour pressure of water is the pressure at which water vapour issaturated. At higher pressures water would condense. The water vapourpressure is the partial pressure of water vapour in any gas mixturesaturated with water. The water vapour pressure determines thetemperature and pressure necessary for freeze-drying to occur. Vapourpressure of water (mTorr=millitorr; mB=millibar) is shown in the belowtable:

Temp (C.) mTorr mB 0 4579 6.104 −4 3280 4.372 −8 2326 3.097 −12 16322.172 −16 1132 1.506 −20 930 1.032 −24 526 0.6985 −28 351 0.4669 −32 2310.3079 −36 150 0.2020 −40 96.6 0.1238 −44 60.9 0.0809 −48 37.8 0.0502−52 23.0 0.0300 −56 13.8 0.0183 −60 8.0 0.0107 −64 4.6 0.0061 −68 2.60.0034 −72 1.4 0.0018

The secondary drying phase aims to remove unfrozen water molecules,since the ice was removed in the primary drying phase. This part of thefreeze-drying process is governed by the material's adsorptionisotherms. In this phase, the temperature is raised higher than in theprimary drying phase, and can even be above 0° C., to break anyphysico-chemical interactions that have formed between the watermolecules and the frozen material. Usually the pressure is also loweredin this stage to encourage desorption (typically in the range ofmicrobars). However, there are products that benefit from increasedpressure as well.

After the freeze-drying process is complete, the vacuum may be brokenwith an inert gas, such as nitrogen, before the material is sealed.

In one embodiment, the vacuum is retained in the product chamber toallow for easy addition of liquid for reconstitution.

At the end of the operation, the final residual water content in thefreeze-dried product is in general very low, such as around 2% or lower.

The freeze-drying process transforms the paste into a “cake-like” drycomposition, which upon addition of an adequate amount of an aqueousmedium, such as water, will form a ready-to use paste spontaneously,i.e. no mechanical mixing/reconstitution is required for said paste toform.

In an alternative embodiment of the present disclosure involving vacuumexpansion of the paste prior to drying, the expanded paste is not frozenprior to drying of the paste. Neither is the paste dried byfreeze-drying. Rather the low vacuum is upheld while the paste is driedby subjecting the expanded paste to an increased temperature until thepaste is dry. The increased temperature is typically in the range ofabout 30-200° C., such as about 50° C. to about 150° C.

Outer Packaging

In one embodiment the dry composition contained within e.g. a medicaldelivery device, such as the herein disclosed syringe, or othercontainment unit, is further contained within an outer packaging so thatthe product is kept sterile until use. This will allow the user toremove the outer packaging and transfer the haemostatic composition intoa sterile field.

The outer packaging is usually made from a flexible, semi-rigid or rigidmaterial and typically consists of materials such as plastic, aluminiumfoil and/or plastic laminate, where the plastic may be selected from thegroup consisting of PET, PETG, PE, LLDPE, CPP, PA, PETP, METPET, Tyvekand optionally bonded with an adhesive, such as polyurethane, orco-extruded.

In one embodiment, the outer packaging is an aluminium foil outerpackaging. The outer packaging preferably forms a complete barrier tomoisture.

The outer packaging is preferably able to endure sterilisation treatmentsuch as by radiation.

Sterilisation

The dry composition of the present disclosure is preferably sterile.This can be by aseptic production or by any suitable sterilisationtechnique known in the art. The sterilisation preferably occurs afterthe packaging step, i.e. when the dry composition is contained within anouter packaging. Thus, in a preferred embodiment sterilisation isterminal sterilisation.

Sterilisation refers to any process that effectively kills or eliminatestransmissible agents (such as fungi, bacteria, viruses, prions and sporeforms etc.). Sterilisation of the dry composition can be achievedthrough e.g. application of heat, chemicals, and irradiation. Heatsterilization include autoclaving (uses steam at high temperatures) anddry heat; radiation sterilisation include X-rays, gamma and beta rays,UV light and subatomic particles; chemical sterilisation include usingethylene oxide gas, ozone, chlorine bleach, glutaraldehyde,formaldehyde, ortho phthalaldehyde, hydrogen peroxide and peraceticacid.

In one embodiment, the dry composition is sterilised by irradiation,e.g. ionizing irradiation, so as to provide sterility to thecomposition. Such irradiation may include e-beam (beta irradiation) orgamma irradiation. The level of irradiation and conditions forsterilisation, including the time that the composition is irradiated,are those that provide sterile compositions. Sterilisation conditionsare similar to those currently utilized in the preparation ofhaemostatic loose powders currently available. Once having the benefitof this disclosure, one skilled in the art will be able to readilydetermine the level of irradiation necessary to provide sterilecompositions.

When thrombin or other sensitive bioactive agents are present in thedried product, sterilisation is usually performed as terminalsterilisation with about 25 kGy or less of beta or gamma irradiation.

In one embodiment, sterilisation is performed with ethylene oxide.

Sterilisation with dry heat may typically be carried out by heating thedry haemostatic composition to a temperature between 100° C. and 250°C., such as about 110° C. to about 200° C. In particular the temperaturemay be in the range of 110-160° C., e.g. in the range of 110-140° C., orin the range of 120-180° C., or in the range of 130-170° C., or in therange of 130-160° C., or in the range of 120-150° C. Heat sterilisationis usually not utilised when the dry composition contains thrombin,since heat treatment would inactivate the thrombin.

In one embodiment, the dry haemostatic composition is not sterilisedafter packaging.

When the dry haemostatic composition is manufactured by asepticproduction techniques, the product is already sterile when placed in theouter packaging and no further sterilisation is required. Thus, in oneembodiment the present disclosure relates to a composition produced byaseptic techniques.

Reconstitution

The present inventors have found that a dry composition prepared by thepresently disclosed methods efficiently reconstitutes to form a flowablepaste having a soft consistency suitable for use in haemostatic andwound healing procedures. The dry composition reconstitutesspontaneously, i.e. without any mechanical mixing required.

The dry composition is reconstituted by adding a suitable aqueousmedium. The aqueous medium may be added by any suitable mechanism.Preferably, the aqueous medium is sterile and compatible with surgicaluse.

The aqueous medium is added in an amount sufficient to obtain a wetpaste having a desired content of the biocompatible polymer. In oneembodiment, the volume of liquid added to the dry compositioncorresponds essentially to the volume of liquid which was removed by thedrying procedure. In case a thinner paste composition is desired, moreliquid can be added to the dried paste than was initially removed by thedrying procedure.

Preferably, the paste is reconstituted by adding an amount of liquid toa container, such as a medical delivery device, having the dried pastecomposition disposed therein, even more preferred to the same containerwhich held the paste during drying.

In one embodiment, the dry composition is reconstituted by attaching asecond container holding an amount of an aqueous medium to the firstcontainer holding the dry composition.

Preferably, the container comprising the reconstitution liquid isessentially free from air or another gas. The advantage of this is thatreconstitution is independent of how the containers are oriented inspace in relation to each other.

In one embodiment, there is a vacuum inside the product chamber of thefirst container, i.e. the pressure inside the product chamber of thefirst container is less than that of the surroundings, i.e. less thanatmospheric pressure.

In one embodiment, the pressure in the second container is greater thanthe pressure in the first container, the pressure difference allowingfor automatic liquid flow from the second container to the firstcontainer. This can e.g. be achieved by the first container having apressure below atmospheric pressure, while the pressure inside thesecond container is about atmospheric pressure. Thus, upon opening avalve separating the two containers, the aqueous medium is automaticallydrawn into the product chamber of the first container due to thepressure difference. The result is a reconstituted paste, see e.g. FIGS.12-13.

Thus, in one embodiment, the present disclosure relates to a method forreconstituting a dry composition comprising the steps of:

-   -   a) providing a first container comprising a product chamber        containing a dry paste composition and a valve, preferably        wherein the pressure within the product chamber is less than the        surrounding atmospheric pressure,    -   b) providing a second container comprising an aqueous medium,        preferably wherein the pressure within the second container is        greater than the pressure within the product chamber of the        first container,    -   c) connecting the first container and the second container using        suitable connecting means, and    -   d) opening the valve.

In one embodiment, the second container is a collapsible container suchas a plastic bag. Upon attachment to the first container and opening ofthe valve, the bag collapses due to the pressure difference, thusallowing for liquid flow from the bag to the product chamber andreconstitution of the paste as illustrated in FIGS. 12-13.

In another embodiment, the second container is a non-collapsiblecontainer comprising a plunger, such as a rigid- or semi-rigid plasticcontainer. Upon attachment to the first container and opening of thevalve the plunger allows for liquid flow from the aqueous mediumcontainer to the product chamber and reconstitution of the paste withoutexerting manual pressure upon the plunger as illustrated in FIGS. 12-13.

In one embodiment a ready-to-use paste forms spontaneously upon additionof liquid to the dry composition disposed within the container withinless than about 30 seconds, preferably within less than about 20seconds, more preferred within less than about 10 seconds, even morepreferred within less than about 5 seconds, such as less than about 3seconds, for example less than about 2 seconds. The reconstituted pasteusually requires no further mixing or other forms of manipulationsbefore use. Thus, when the dry composition is present in a medicaldelivery device, such as a syringe, it can be applied directly to apatient immediately after liquid addition, e.g. for haemostaticpurposes, by extruding the paste from the medical delivery device to ableeding wound.

In a preferred embodiment, a ready-to-use paste forms within less thanabout 10 seconds, for example less than about 5 seconds, such as lessthan about 3 seconds, for example less than about 2 seconds.

After reconstitution, the container, for example a syringe, such as theherein disclosed syringe, may be fitted with an applicator tip suitablefor administering the paste in a more precise manner as illustrated inFIG. 14.

In one embodiment the applicator tip is bendable or malleable and willmaintain a desired configuration chosen by the user so that it stays atan optimum angle for easy access and exact product placement. Further,it can be cut to a desired length with a pair of nurses dressingscissors or similar type of scissors. These features allow for accurateand convenient application of the paste. In one embodiment theapplicator tip is essentially as described in WO 2011/047753.

In one embodiment, the reconstituted paste has a consistency within therange of about 100 g×sec to about 10,000 g×sec, such as from about 500g×sec to about 5000 g×sec, for example from about 1000 g×sec to about3000 g×sec, such as from about 1500 g×sec to about 2000 g×sec.

In one embodiment, the reconstituted paste has a consistency of lessthan about 5000 g×sec, for example less than about 4000 g×sec, such asless than about 3000 g×sec, for example less than about 2000 g×sec.

A Haemostatic Paste

In one embodiment the present disclosure relates to a paste suitable foruse in haemostatic procedures. The haemostatic paste may be obtained bythe methods disclosed herein. The paste of the present disclosure has adesirable soft and light consistency as compared to pastes currentlyknown in the art.

The haemostatic paste of the present disclosure comprises abiocompatible polymer and preferably has a consistency of less than 5000g×sec.

The biocompatible polymer is usually in the form of substantiallywater-insoluble particles. Preferably, it is a cross-linkedbiocompatible polymer suitable for use in haemostasis and/or woundhealing, such as cross-linked gelatine particles as described elsewhereherein.

The paste may be made using any aqueous medium suitable for preparing apaste known to a person of skill as described elsewhere herein.

In one embodiment, the consistency of the paste is less than about 4500g×sec.

In one embodiment, the consistency of the paste is less than about 4000g×sec.

In one embodiment, the consistency of the paste is less than about 3500g×sec.

In one embodiment, the consistency of the paste is less than about 3000g×sec.

In one embodiment, the consistency of the paste is less than about 2500g×sec.

In one embodiment, the consistency of the paste is less than about 2000g×sec.

In one embodiment, the consistency of the paste is within the range ofabout 100 g×sec to about 5000 g×sec, such as from about 500 g×sec toabout 4000 g×sec, for example from about 500 g×sec to about 3500 g×sec,such as from about 500 g×sec to about 3000 g×sec, for example from about500 g×sec to about 2500 g×sec, such as from about 500 g×sec to about2000 g×sec.

In one embodiment, the consistency of the paste is within the range ofabout 1000 g×sec to about 4000 g×sec, for example from about 1000 g×secto about 3500 g×sec, such as from about 1000 g×sec to about 3000 g×sec,for example from about 1000 g×sec to about 2500 g×sec, such as fromabout 1000 g×sec to about 2000 g×sec.

The paste of the present disclosure may further comprise one or morehydrophilic compounds as described elsewhere herein. For example, thepaste may comprise a polyol as hydrophilic compound, such as a sugaralcohol, at a concentration of at least 1%, more preferred at least 2%,such as at least 3%, for example at least 4%, such as at least 5%. Inone embodiment, the sugar alcohol is mannitol.

The paste of the present disclosure may further comprise one or morefurther compounds and/or bioactive agents and/or extrusion enhancers asdescribed elsewhere herein. Preferably, the paste of the presentdisclosure comprises thrombin as bioactive agent.

In a specific embodiment, the present disclosure relates to a pastesuitable for use in haemostasis comprising:

a) a biocompatible polymer at about 10% to about 40%,b) an aqueous medium such as water, and optionally one or more ofc) a hydrophilic compound at about 1% to about 20%,d) a bioactive agent, ande) an extrusion enhancer,wherein said paste has a consistency of less than 5000 g×sec.

In one embodiment, the present disclosure relates to a syringecomprising said paste.

Medical Use

The present disclosure further relates to use of the dry composition orthe paste disclosed herein for promoting haemostasis and/or woundhealing in an individual in need thereof.

The paste of the present disclosure has a soft consistency, which may bepreferable in certain types of surgeries. In addition, surgeonpreferences also vary with regards to the consistency of the pastes,where some surgeons prefer a softer consistency than others.Consequently, the presently disclosed dry composition and paste maysatisfy the need of surgeons having a preference for a softer pasteconsistency.

The paste of the present disclosure may e.g. be used in an array ofsurgical procedures wherein bleeding control is desired. Haemostaticproducts in paste form are able to conform efficiently to irregularsurfaces and are therefore useful for providing rapid haemostasis onrough or uneven surfaces where haemostatic sponges are not efficient.

Currently available haemostatic pastes (e.g. Floseal® and Surgiflo®) areusually prepared (i.e. reconstituted) directly at the surgical site atthe time of need by the medical practitioner, i.e. the doctors ornurses, by addition of liquid to a container, such as a syringe,containing an amount of a biocompatible polymer. The biocompatiblepolymer may be pre-wetted with the liquid or be essentially dry(free-flowing powder). The paste is thus often prepared under extremelystressful conditions and it is therefore essential that the process forpreparing the paste is simple and fast to ensure that the bleeding isarrested as quickly as possible and that no mistakes are made whilepreparing the paste such that the nurse can keep focus on the needs ofthe surgeon instead of on preparing the haemostat. It is also importantthat the consistency of the paste is suitable for the particularsurgical procedure, that the consistency of the product is independentfrom preparation to preparation, and that the consistency of thereconstituted paste does not very substantially over time (afterpreparation).

Due to the time-consuming and often intricate preparation steps requiredfor reconstituting the currently available flowable paste products, theyare often pre-prepared in the OR before surgery in case they are neededunder surgery. Consequently, unused product is thus often discardedbecause the surgeon does not use as much of the product as expected.Unused product must also be discarded if the time limit for using thereconstituted product is expired. This causes unnecessary high OR costs.

The preparation of the paste of the present disclosure is simple andfast—the dry composition reconstitutes to form a flowable paste withinseconds of coming into contact with the aqueous medium. Importantly, nomechanical mixing steps are required. Thus, there is no need forpre-preparing the paste prior to a surgical procedure and OR costs canbe kept at a minimum.

As the reconstitution of the dry composition of the present disclosureis independent from mechanical mixing, the consistency of thereconstituted paste will always be the same when the correct amount ofliquid is added. This is not always the case with the conventionalpastes, where the consistency of the paste may depend on the forceapplied and time spent mixing. That no mechanical mixing is requiredalso means that less time is spent preparing the paste, which in turnleads to increased patient safety, both due to the fact that thehaemostatic paste can be applied to the patient faster and that thesimple preparation method decreases the likelihood of mistakes beingmade during the preparation of the haemostatic paste.

When thrombin is comprised within the dry composition, the inventionfurther has the advantage over conventional pastes in that it avoids thetime-consuming and error-prone thrombin dilution and addition stepsinvolved in current methods for preparing flowables.

Another notable advantage of the dry composition of the presentinvention is that a kit consisting of fewer components can be preparedas compared to e.g. current haemostatic flowable kits. All there isrequired to prepare a flowable paste composition in the OR is the drycomposition as described herein comprised within a medical deliverydevice and a container comprising an aqueous medium for reconstitution.Upon connection of the two, a ready-to-use flowable paste containing allnecessary agents for effective haemostasis including thrombin is formedspontaneously when the aqueous medium is automatically drawn into themedical delivery device containing the dry composition. Thus, no extrasyringes, vial adapters, needles and mixing bowls are required with theproduct prepared according to the methods of the present disclosure.This means that the manufacturing costs can be decreased and alsoensures good patient safety, since there are less components for the ORstaff to keep track of during surgery. Needle-free preparation of thehaemostat also ensures the safety of the OR staff.

In one embodiment the present disclosure relates to a method forarresting bleeding/promoting haemostasis in an individual in needthereof by application of the paste of the present disclosure to a siteof bleeding.

The paste of the present disclosure may be used for any type of surgeryincluding general surgery, cardiothoracic surgery, vascular surgery,plastic surgery, paediatric surgery, colorectal surgery, transplantsurgery, surgical oncology, trauma surgery, endocrine surgery, breastsurgery, skin surgery, otolaryngology, gynaecology, oral andmaxillofacial surgery, dental Surgery, orthopaedic surgery,neurosurgery, ophthalmology, podiatric surgery, urology.

In one embodiment the present disclosure relates to a method forpromoting wound healing in an individual in need thereof by applicationof the paste of the present disclosure to a wound.

A “wound” refers broadly to injuries to the skin and/or underlying(subcutaneous) tissue initiated in different ways (e.g., pressure soresfrom extended bed rest and wounds induced by trauma) and with varyingcharacteristics. Wounds may be classified into one of four gradesdepending on the depth of the wound: i) Grade I: wounds limited to theepithelium; ii) Grade II: wounds extending into the dermis; iii) GradeIII: wounds extending into the subcutaneous tissue; and iv) Grade IV (orfull-thickness wounds): wounds wherein bones are exposed (e.g., a bonypressure point such as the greater trochanter or the sacrum). Thepresent disclosure relates to treatment of any type of wound mentionedabove using the paste of the present disclosure.

The treatment of a wound can in principle result in healing of the woundor in accelerated healing of the wound. The accelerated healing can be aresult of e.g. administration of a wound-healing promoting substance.Alternatively, the wound healing can be promoted by preventing bacterialor viral infection, or by reducing the risk of such an infection whichwould otherwise have prolonged the wound treatment process.

In one embodiment the present disclosure relates to a method forpromoting bone and/or tendon healing in an individual in need thereof byapplication of the paste of the present disclosure to the injuredbone/tendon.

The “individual” referred to herein may be any mammal, including, butnot limited to, mammals of the order Rodentia, such as mice andhamsters, and mammals of the order Logomorpha, such as rabbits. It ispreferred that the mammals are from the order Carnivora, includingFelines (cats) and Canines (dogs). It is more preferred that the mammalsare from the order Artiodactyla, including Bovines (cows) and Swines(pigs) or of the order Perssodactyla, including Equines (horses). It ismost preferred that the mammals are of the order Primates, Ceboids, orSimoids (monkeys) or of the order Anthropoids (humans and apes). Anespecially preferred mammal is the human.

In one embodiment the present disclosure relates to the dry compositionas disclosed herein, for use in the treatment of a wound, e.g. forarresting bleeding or for promoting wound healing.

A Haemostatic Kit

The present disclosure further relates to a haemostatic kit comprisingthe dry composition of the present disclosure and an amount of aqueousmedium matched to the amount of the dry composition so that uponaddition of the aqueous medium, a haemostatic paste of a consistencysuitable for use as a haemostatic paste will form without the need formechanical mixing.

Hence, in one embodiment the present disclosure relates to a haemostatickit comprising:

-   -   a) a first container comprising the dry composition obtained by        the method of the present disclosure,    -   b) a second container comprising an aqueous medium, and    -   c) optionally an outer packaging.

In a further embodiment the present disclosure relates to a haemostatickit comprising:

-   -   a) the presently disclosed syringe comprising a dry composition    -   b) a container comprising an aqueous medium, and    -   c) optionally an outer packaging.

The dry composition may be any dry composition, in particular a drycomposition that upon addition of the aqueous medium, a haemostaticpaste will form of a consistency suitable for use as a haemostaticpaste, such as form spontaneously within seconds, such as a drycomposition obtained by the method of the present disclosure.

In one embodiment, the dry composition comprises thrombin.

In one embodiment, the kit further comprises one or more applicatortips.

The kit may optionally contain instructions for use of the kit.

Example 1 Materials

50 g Gelatine powder (milled cross-linked gelatine sponges)200 ml buffer

x g Polyol 50% Benzalkoniumchloride (BAC)

0.9% Saline solution

Equipment

Freeze dryer: Christ Alpha 1-4 LSC

Mixer: Kenwood, Major KM616 Method

Buffer solution:Add 2.0 g±0.1 g BAC (50%) to a 250 mL blue cap bottleAdd 98.0 g±0.5 g water to the BACMix for 2 minutes using magnetic stirring—this is the BAC stock solutionAdd 10 g±0.5 g BAC stock solutionAdd water to the 2000 mL markPlace a stopper in the flask and turn it upside down a few timesMix by magnetic stirring for 5±1 minutes

Paste:

Dissolve x g polyol in 200 ml buffer solution under stirring in themixer. Add 50 g gelatine powder and mix with the dissolved polyol untila homogeneous paste is obtained, approximately 5 minutes.

Freeze-Drying:

The resulting paste was filled into 10 ml single use plastic syringes(5.5 ml per syringe) comprising a lyophilisation bypass channel andplaced at −30° C. for minimum 4 h. The frozen paste was transferred tothe freeze-dryer and freeze-dried until dry for approximately 15 h. Atthe end of the drying cycle the shelves of the lyophiliser werecollapsed, thereby moving the plunger and closing the lyo bypasschannel. The pressure in the lyophiliser chamber was then brought toambient pressure leaving a vacuum in the product chamber.

Reconstitution:

The dry haemostatic composition was reconstituted by connecting thesyringe comprising the dry composition to a collapsible plastic bagcontaining water (8 ml). No mechanical mixing or stirring was used. Thewater was added to the dry composition by utilising the vacuum insidethe product chamber, and the composition was left untouched until apaste was re-formed. The vacuum inside the product chamber of thesyringe causes the water to be automatically drawn into the syringe fromthe container holding the water.

Results

The different formulations were tested for time to reconstitution, i.e.the time needed for a paste suitable for haemostatic purposes tospontaneously form without mechanical agitation of any sorts.

Pastes comprising different polyols were made, dried and reconstitutedaccording to the directions above. The contents of the pastes are shownin the tables below.

Content wet Content dry Content wet Content dry [g] [g] [W/W %] [W/W %]Gelatine 50.00 50.00 18.52 70.41 Mannitol 20.00 20.00 7.41 28.17 BAC0.01 0.01 0.00 0.01 H₂0 200 1.00 74.07 1.41 SUM 270.01 71.01 100 100Content wet Content dry Content wet Content dry [g] [g] [%] [%] Gelatine50.00 50.00 18.52 70.41 Xylitol 20.00 20.00 7.41 28.17 BAC 0.01 0.010.00 0.01 H₂0 200 1.00 74.07 1.41 SUM 270.01 71.01 100 100 Content wetContent dry Content wet Content dry [g] [g] [%] [%] Gelatine 50.00 50.0018.52 70.41 Trehalose 20.00 20.00 7.41 28.17 BAC 0.01 0.01 0.00 0.01 H₂0200 1.00 74.07 1.41 SUM 270.01 71.01 100 100 Content wet Content dryContent wet Content dry [g] [g] [%] [%] Gelatine 50.00 50.00 18.52 70.41Maltitol 20.00 20.00 7.41 28.17 BAC 0.01 0.01 0.00 0.01 H₂0 200 1.0074.07 1.41 SUM 270.01 71.01 100 100 Content wet Content dry Content wetContent dry [g] [g] [%] [%] Gelatine 50.00 50.00 18.52 70.41 Sorbitol20.00 20.00 7.41 28.17 BAC 0.01 0.01 0.00 0.01 H₂0 200 1.00 74.07 1.41SUM 270.01 71.01 100 100

The polyol:gelatine ratio in the dry compositions was approximately0.4:1.

The spontaneous reconstitution time of the pastes comprising differentpolyols made according to the tables above is shown in the table belowand in FIG. 1. The experiments were repeated 5 times for each polyol.

Mannitol Xylitol Trehalose Maltitol Sorbitol 1 7 14 11 14 29 2 9 31 2814 28 3 9 20 16 23 29 4 10 30 29 16 35 5 9 31 23 22 32 Average 8.8 25.221.4 17.8 30.6 reconstitution time [sec] Std 1.1 7.8 7.8 4.4 2.9

The experiment shows that different kinds of polyols can be used formaking a freeze-dried gelatine paste that will reconstitutespontaneously upon addition of an aqueous medium within less than about30 seconds. The reconstituted paste has a consistency suitable fordirect use as a haemostatic paste.

Example 2. Thrombin

Thrombin was included in the below paste formulation at a theoreticalconcentration of 2500 IU/product. The paste was made at room temperature(about 20° C.) and mixed as described in Example 1.

The dried paste had a spontaneous reconstitution time of about 5seconds. The contents of the paste formulation are specified in thetable below in the paste (wet) and the dried composition (dry)respectively.

Paste Content wet Content dry Content wet Content dry Formulation [g][g] [%] [%] Gelatine 50.00 50.00 18.18 56.65 Mannitol 20.00 20.00 7.2722.66 Glycerol 12.30 12.30 4.47 13.94 (buffer) Glycerol 5.00 5.00 1.825.67 (added) BAC 0.01 0.01 0.00 0.01 NaCl 0.01 0.01 0.00 0.01 H₂0 187.680.94 68.25 1.06 SUM 275.00 88.26 100 100

The total polyol concentration, i.e. mannitol and glycerol, in the pastewas 13.56% and after drying 42.27%.

The polyol:gelatine ratio in the dry composition was approximately0.75:1.

The paste was dried by freeze-drying and reconstituted as described inExample 1.

The thrombin activity was measured in the reconstituted paste. Theresults are shown in the table below.

Thrombin Activity - Freeze-dried composition in syringe [IU/product]2519.60 2884.94 2796.71 Mean activity: 2733.75

No loss of thrombin activity was measured in the reconstituted paste.

The results show that it is not strictly necessary to perform the mixingof the paste at low temperatures to avoid loss of thrombin activity asno decrease in thrombin activity was found when mixing was performed atambient temperatures.

Example 3. Vacuum Expansion of Pastes Prior to Freeze-Drying

Gelatine pastes comprising mannitol were prepared essentially asdescribed in Example 1 and aliquoted into 10 ml single-use syringes,each syringe receiving 4 g of the paste. The contents of the pasteformulation are specified in the table below in the paste (wet) and thedried composition (dry) respectively.

Content wet Content dry Content wet Content dry [g] [g] [W/W %] [W/W %]Gelatine 50.00 50.00 18.52 70.41 Mannitol 20.00 20.00 7.41 28.17 BAC0.01 0.01 0.00 0.01 H₂0 200 1.00 74.07 1.41 SUM 270.01 71.01 100 100

The prepared pastes were either freeze dried directly as described inExample 1 (standard lyophilisation) or subjected to a low vacuum ofabout 850 mbar, followed by a freezing step to −40° C. without releasingthe vacuum and finally freeze dried essentially as described in Example1 (vacuum expanded lyophilisation). Vacuum expansion was performed atambient temperature, i.e. about 20° C. Upon exposure of the pastes tothe decreased pressure, i.e. vacuum, the pastes expanded in volumealmost instantaneously.

Before vacuum expansion, the density of the gelatine paste wasapproximately about 0.7 g/ml. After vacuum expansion, the density of thepaste was approximately about 0.5 g/ml corresponding to a decrease inthe density of the paste by about a factor 0.72 and a concurrentincrease in the volume of the paste by about a factor 1.4.

The lyophilised products were reconstituted essentially as described inExample 1 by adding 5.5 ml saline to the lyophilised product and theamount of time for the paste to fully absorb the saline was measured.The vacuum inside the product chamber of the syringes automaticallydraws in the liquid. Both vacuum expanded and standard pastes were softand moist after reconstitution and exhibited comparable absorptioncapacities. The consistency of the reconstituted pastes was consideredsuitable for use on a patient. The reconstituted pastes had a slightlyoff white/yellowish colour.

The reconstitution time for the dried paste compositions is shown in thebelow table and in FIG. 2. The experiments were repeated 5 times (n=5).

Standard Vacuum expanded n lyophilization lyophilization 1 7 1 2 9 2 3 91 4 10 1 5 9 1 Average 8.8 1.2 reconstitution time [sec] Std 1.1 0.4

The inventors surprisingly found that by subjecting the paste to vacuumprior to freezing, the haemostatic dried paste reconstituted more thanseven times faster than pastes that had not been vacuum expanded.Reconstitution required no mechanical agitation, mixing or stirring ofany kind and a ready-to-use haemostatic paste of a consistency suitablefor direct use in haemostatic procedures was formed within seconds.

Example 4. Density of Dry Vacuum Expanded Paste

Gelatine pastes comprising mannitol were prepared as described inExamples 1 and 3. The pastes were vacuum expanded using different vacuumlevels (1000 mbar (no vacuum), 850 mbar and 600 mbar) and then frozenand freeze-dried as described in Example 3.

The density of the dry paste compositions is shown in the below tableand in FIG. 15.

Pressure Ø H Mass Volume Density [mbar] [cm] [cm] [g] [cm³] [g/cm³] 10001.4 4.9 1.3 30.2 0.043 850 1.5 5.5 1.4 38.9 0.035 600 1.8 6.0 1.4 61.10.023

The dry compositions reconstituted spontaneously to form soft and moistpastes suitable for haemostatic and/or wound healing use.

The results show that different pressures may be used to expand thepaste prior to drying.

The results further show that the pressure used for expansion affectsthe density of the dry paste composition. Indeed, there seems to be agood correlation between the pressure and the density of the drycomposition with lower pressures resulting in lower densities of thefinal dry paste composition.

Example 5. Effect of Vacuum Expansion and Polyol Concentration

Gelatine pastes comprising different amounts of mannitol (no mannitol,medium mannitol (approx. 3.9%) or high mannitol (approx. 7.4%)) wereprepared essentially as described in Example 1 with the exception that aVirtis Genesis 35 freeze-dryer was used. Portions of paste werealiquoted into 10 ml single-use syringes having vacumm bypass, eachsyringe receiving 4 g of the paste. The contents of the pasteformulation are specified in the table below in the paste (wet) and thedried composition (dry) respectively.

No Content wet Content dry Content wet Content dry Mannitol [g] [g] [W/W%] [W/W %] Gelatine 50.00 50.00 20.00 98.02 Mannitol 0.00 0.00 0.00 0.00BAC 0.01 0.01 0.00 0.02 H₂0 200.00 1.00 80.00 1.96 SUM 250.01 51.01100.00 100.00

Medium Content wet Content dry Content wet Content dry Mannitol [g] [g][W/W %] [W/W %] Gelatine 50.00 50.00 19.23 81.95 Mannitol 10.00 10.003.85 16.39 BAC 0.01 0.01 0.00 0.02 H₂0 200.00 1.00 76.92 1.64 SUM 260.0161.01 100.00 100.00

High Content wet Content dry Content wet Content dry Mannitol [g] [g][W/W %] [W/W %] Gelatine 50.00 50.00 18.52 70.41 Mannitol 20.00 20.007.41 28.17 BAC 0.01 0.01 0.00 0.01 H₂0 200.00 1.00 74.07 1.41 SUM 270.0171.01 100.00 100.00

The prepared pastes were either freeze dried directly as described inExample 1 (no expansion) or vacuum expanded by exposure to a low vacuumof about 850 mbar, followed by a freezing step to −40° C. withoutreleasing the vacuum and finally freeze dried essentially as describedin Example 1 (vacuum expansion). Vacuum expansion was performed atambient temperature, i.e. about 20° C.

The lyophilised products were reconstituted by adding 5.5 ml saline tothe lyophilised product in the syringe and the amount of time for thepaste to fully absorb the saline was measured. No mechanical mixing wasperformed. The reconstituted pastes were soft and moist and exhibitedcomparable absorption capacities. However, the consistency of thenon-expanded gelatine pastes without mannitol were inferior to pastescontaining mannitol and/or pastes having been expanded by vacuum. Thereconstituted pastes had a slightly off white/yellowish colour.

The average reconstitution time for the dried paste compositions isshown in the below table and in FIG. 21. Each experiment was repeated 5times (n=5).

Mannitol Average reconstitution concentration time in seconds +/− [wt %]standard deviation No expansion 0  44.8 +/− 14.2* No expansion 3.9  37.2+/− 14.7 No expansion 7.4 14.3 +/− 9.7 Expansion 0 13.8 +/− 2.7Expansion 3.9 12.6 +/− 7.2 Expansion 7.4  3.0 +/− 1.4 *The consistencyof the reconstituted paste was clearly inferior to pastes containingmannitol and/or pastes having been expanded by vacuum.

Vacuum expansion of the gelatine pastes prior to freeze-drying greatlyreduced the reconstitution time of dried gelatine paste compositionsboth with and without mannitol. In fact, vacuum expansion was able toreduce the spontaneous reconstitution time of the gelatine pastes withabout a factor 3 or more. The spontaneous reconstitution time wasfurther improved, i.e. decreased, by inclusion of mannitol in the drycompositions. Mannitol also improved the consistency of thereconstituted pastes.

Gelatine pastes containing 7.4% polyethylene glycol (PEG) were alsoprepared as above, vacuum expanded and freeze-dried. The contents of thepaste formulation are specified in the table below in the paste (wet)and the dried composition (dry) respectively.

Content wet Content dry Content wet Content dry PEG [g] [g] [W/W %] [W/W%] Gelatine 50.00 50.00 18.52 70.41 PEG 20.00 20.00 7.41 28.17 BAC 0.010.01 0.00 0.01 H₂0 200.00 1.00 74.07 1.41 SUM 270.01 71.01 100.00 100.00

The average reconstitution time for the dried paste compositionscomprising PEG was 8.2+/−2.4 seconds (n=5). Dried vacuum-expandedgelatine pastes containing PEG reconstituted about 1.7 times faster thancontrol (vacuum expanded gelatine paste without any hydrophiliccompounds added) and had a superior consistency. The results are shownin FIG. 22.

The inventors have also discovered that the volume of a paste aliquot isgenerally higher in samples being aliquoted first as opposed to lastfrom a single batch of paste. This is thought to be due to a partialcollapse of the paste over time causing undesirable variations in pastedensity. Such variations in density can lead to undesirable variationsin the reconstitution time. Vacuum expansion of the paste prior todrying is believed to be able to reduce or even eliminate suchdifferences in paste density which can occur between the first and thelast portions of pastes being aliquoted from a single paste batch.

In conclusion, the results show that vacuum expansion before dryinggreatly improves the reconstitution rate and is able to provide moreconsistent results with regards to the reconstitution time. Thespontaneous reconstitution rate can be further improved by inclusion ofincreasing amounts of polyols in the dried paste compositions. Inaddition, inclusion of hydrophilic compounds, such as polyols, in thedried paste compositions also improved the consistency of thereconstituted pastes.

Example 6. Effect of Polyols and Vacuum Expansion on the Consistency ofSodium Bicarbonate-Containing Reconstituted Pastes Materials

Paste without Polyol:50 g Gelatine powder (milled Surgifoam sponges)200 ml 0.005% BAC w/w in MQ water

1% NaHCO₃(Sigma) Polyol Containing Paste:

50 g Gelatine powder (milled Surgifoam sponges)200 ml 0.005% BAC w/w in MQ water

20 g D-Mannitol (Sigma) 1% NaHCO3(Sigma)

A 2.5% citric acid solution was used for reconstituting the dried pastecompositions. The pH of the solution was approximately 2.

Equipment

Freeze dryer: Genesis 35

Mixer: Kenwood, Major KM616

Texture analyser: TA.XT.plus, Stable micro systems

Method Preparing the Pastes

To prepare pastes without polyol, 50 g gelatine powder was placed in amixing bowl and 200 ml 0.005% BAC w/w in MQ solution was added andstirred until a homogeneous paste was obtained (approximately 10 minutesof mixing in the Kenwood mixer). The resulting paste was weighed andNaHCO₃ added in an amount resulting in a 1% w/w NaHCO₃ containing paste.The NaHCO₃ was mixed into the paste for an additional 2 minutes.

The polyol containing paste was made similarly to the above procedure,except for adding a 200 ml 0.005% BAC w/w in MQ water having 20 gD-Mannitol dissolved in it.

Lyophilisation

The resulting pastes were filled into lyophilisation syringes at 5.5 gportions and the syringes were placed in the lyophiliser. Prior tofreezing, a vacuum of app. 450,000 mtorr (about 600 mbar) was applied toa portion of the samples. The portion of samples which were notsubjected to vacuum expansion prior to freezing were frozen immediatelywhen placed in the lyophiliser. Thereafter, the samples were frozen tobelow −40° C. The samples were then dried in the lyophiliser until dry.

Reconstitution

The dried pastes were reconstituted by addition of 7.0 ml of a 2.5%citric acid solution to each syringe. Specifically, the reconstitutionliquid was added by connecting the syringe containing the dried pastewith another syringe containing the citric acid solution and opening avalve allowing for communication between the two syringes. Due to thereduced pressure within the syringe containing the dried paste, thereconstitution liquid is automatically drawn into the syringe containingthe dried paste. All of the samples reconstituted spontaneously withoutany mechanical mixing required. The spontaneous reconstitution time ofthe different samples varied according to the table shown in the resultssection below.

Texture Analysis

The consistency of the reconstituted pastes was tested using a textureanalyser (TA.XT.plus, Stable micro systems).

TA Settings

Test mode compression Pre-test speed 5.00 mm/sec Test speed 0.5 mm/secPost-test speed 10 mm/sec Distance 30.0 mm Trigger type Auto Triggerforce 4.0 g Probe P/0.5R ½″ Dia Cylinder

Results

The contents of the compositions in wet and dry state were as follows:

1% NaHCO₃, −polyol:

Content wet Content dry Content wet Content dry Excipient [g] [g] [W/W%] [W/W %] Gelatine 50.00 50.00 19.78 93.04 Mannitol 0.00 0.00 0.00 0.00BAC 0.01 0.01 0.00 0.02 NaHCO₃ 2.73 2.73 1.00 5.08 H₂0 200.00 1.00 79.131.86 SUM 252.74 53.74 100.00 100.001% NaHCO₃, +polyol (mannitol):

Content wet Content dry Content wet Content dry Excipient [g] [g] [W/W%] [W/W %] Gelatine 50.00 50.00 18.33 67.81 Mannitol 20.00 20.00 7.3327.12 BAC 0.01 0.01 0.00 0.01 NaHCO₃ 2.73 2.73 1.00 3.70 H₂0 200.00 1.0073.33 1.36 SUM 272.74 73.74 100.00 100.00

The consistencies were calculated as area under the resulting curve andthe results are shown in the below table. Also shown is the averagereconstitution time of the samples. All samples reconstitutedspontaneously without mechanical mixing although the reconstitution timevaried between the groups.

Average consistency Average reconstitution Group (N = 5 for each [g*sec]+/− standard time [sec] +/− standard group) deviation deviation −polyol− vacuum 2120 +/− 557 74 +/− 12 expansion −polyol + vacuum 2237 +/− 44922 +/− 6  expansion +polyol − vacuum 2411 +/− 641 45 +/− 9  expansion+polyol + vacuum 1725 +/− 463 9 +/− 2 expansion

It was observed that the inclusion of NaHCO₃ resulted in pastes (priorto drying) which on visual inspection seemed to be more dense thanpastes prepared without NaHCO₃. This may explain the longerreconstitution times observed as compared to freeze-dried pastesprepared without NaHCO₃, for instance the samples of Example 5 herein.

There is no significant difference in paste consistency between the fourtested groups of samples (+/−polyol, +/−vacuum expansion) (P=0.3,Welch's t-test).

Conclusion

The paste consistency was not altered significantly in response to theaddition of polyol or in response to the exposure to vacuum expansion. Asoft smooth consistency was achieved in all four test conditions,although the reconstitution time varied depending on the inclusion ofpolyol and the use of vacuum expansion prior to freeze-drying. Uponreconstitution, the NaHCO₃ in the dry compositions reacts with the acidin the reconstitution liquid and CO₂ will form. The CO₂ expands insidethe paste, thereby altering the consistency regardless of the presenceof polyol or the exposure to vacuum expansion.

Example 7. Effect of Varying the Concentration of Sodium Bicarbonate onthe Consistency of Reconstituted Pastes Materials NaHCO₃ ContainingPaste:

100 g Gelatine powder (milled Surgifoam sponges)400 ml 0.005% BAC w/w in MQ water

40 g D-Mannitol (Sigma) x g NaHCO₃(Sigma) Standard Paste (Control):

50 g Gelatine powder (milled Surgifoam sponges)200 ml 0.005% BAC w/w in MQ water

20 g D-Mannitol (Sigma)

A 2.5% citric acid solution was used for reconstituting the dried pastecompositions. The pH of the solution was about 2.

Equipment

Freeze dryer: Genesis 35

Mixer: Kenwood, Major KM616

Texture analyser: TA.XT.plus, Stable micro systems

Method Preparing the Pastes

40 g mannitol was completely dissolved in 400 ml 0.005% BAC w/w in MQsolution under stirring. 100 g gelatine powder was added and mixed withthe dissolved Mannitol solution until a substantially homogeneous pastewas obtained (approximately 10 minutes of mixing in the Kenwood mixer).The resulting paste was divided into two equally sized portions (265.6g) and x g of NaHCO₃ was added to each portion according to the belowtable and mixed for an additional 2 minutes.

Formulation x: NaHCO₃ % w/w NaHCO₃ [g] 1% NaHCO₃ 2.73 0.5% NaHCO₃ 1.360% NaHCO₃ 0

The standard paste was prepared in a similar manner except for addingthe NaHCO₃ and the final mixing step.

Lyophilisation

The resulting pastes were filled into lyophilisation syringes at 5.5 gportions and the syringes were placed in the lyophiliser. Prior tofreezing, a vacuum of app. 450,000 mtorr (about 600 mbar, i.e. about 400mbar less than ambient pressure) was applied to the samples. Thereafter,the samples were frozen to below −40° C. The samples were then dried inthe lyophiliser until dry.

Reconstitution

The dried pastes were reconstituted by addition of 7.0 ml of a 2.5%citric acid solution. Specifically, the reconstitution liquid was addedby connecting the syringe containing the dried paste with anothersyringe containing the citric acid solution and opening a valve allowingfor communication between the two syringes. Due to the reduced pressurewithin the syringe containing the dried paste, the reconstitution liquidis automatically drawn into the syringe containing the dried paste. Thedried pastes reconstituted spontaneously within less than 10 secondswithout any mechanical mixing required.

Texture Analysis

The consistency of the different formulations was tested using a textureanalyser (TA.XT.plus, Stable micro systems). TA settings were asindicated for Example 6.

Results

The contents of the compositions in wet and dry state were as follows:

0% NaHCO₃ in Wet Paste Prior to Drying:

Content wet Content dry Content wet Content dry Excipient [g] [g] [W/W%] [W/W %] Gelatine 50.00 50.00 18.52 70.41 Mannitol 20.00 20.00 7.4128.17 BAC 0.01 0.01 0.00 0.01 H₂0 200.00 1.00 74.07 1.41 SUM 270.0171.01 100.00 100.00

0.5% NaHCO₃ in Wet Paste Prior to Drying:

Content wet Content dry Content wet Content dry Excipient [g] [g] [W/W%] [W/W %] Gelatine 50.00 50.00 18.43 67.81 Mannitol 20.00 20.00 7.3727.12 BAC 0.01 0.01 0.00 0.01 NaHCO₃ 1.36 1.36 0.50 1.88 H₂0 200.00 1.0073.72 1.38 SUM 271.31 72.31 100.00 100.00

1% NaHCO₃ in Wet Paste Prior to Drying:

Content wet Content dry Content wet Content dry Excipient [g] [g] [W/W%] [W/W %] Gelatine 50.00 50.00 18.33 67.81 Mannitol 20.00 20.00 7.3327.12 BAC 0.01 0.01 0.00 0.01 NaHCO₃ 2.73 2.73 1.00 3.70 H₂0 200.00 1.0073.33 1.36 SUM 272.74 73.74 100.00 100.00

The consistencies of the reconstituted pastes were calculated as areaunder the resulting curve and the results are shown in the below table.

Formulation Area [g × sec] +/− standard deviation 0% NaHCO₃ 5183 +/− 8640.5% NaHCO₃ 2829 +/− 802 1% NaHCO₃ 1499 +/− 373

The results are also depicted in FIG. 23.

The study shows that the presence of 0.5% sodium bicarbonate in thepaste prior to drying (corresponding to about 1.9% in the drycomposition), decreases the area under the curve by about 45% while 1%sodium bicarbonate in the paste prior to drying (corresponding to about3.7% in dry composition), decreases the area under the curve by about71% compared to control (0% NaHCO₃). The area under the curve is ameasure for the consistency or softness of the pastes.

The reconstituted pastes comprising sodium carbonate were visibly whiterthan the reconstituted pastes without sodium bicarbonate. The more gas apaste contains, the lighter the colour of the paste will be.

Conclusion

The consistency of the reconstituted pastes softens as the concentrationof NaHCO₃ increases. This is presumably due to the CO₂ formed when thebase NaHCO₃ reacts with the citric acid upon reconstitution of the driedpaste compositions. The CO₂ formed expands inside the paste, therebyaltering the consistency of the pastes. A softer, lighter consistency isdesirable in some applications of haemostatic pastes.

Example 8. Effect of Incorporating an Acid in the Dry Composition andReconstituting with a Base Materials Paste:

50 g Gelatine powder (milled Surgifoam sponges)200 ml 0.005% BAC w/w in MQ water

20 g D-Mannitol (Sigma) 1% Tartaric Acid (Sigma)

A 2.5% NaHCO₃ solution was used for reconstituting the dried pastecompositions. The pH of the solution was about 8.2.

Equipment

Freeze dryer: Genesis 35

Mixer: Kenwood, Major KM616

Texture analyser: TA.XT.plus, Stable micro systems

Method Preparing the Paste

To prepare the paste, 50 g gelatine powder was placed in a mixing bowland 200 ml 0.005% BAC w/w in MQ water having 20 g D-Mannitol dissolvedin it was added and stirred until a homogeneous paste was obtained(approximately 10 minutes of mixing in the Kenwood mixer). The resultingpaste was weighed and tartaric acid added in an amount resulting in a 1%w/w tartaric acid containing paste. The tartaric acid was mixed into thepaste for an additional 2 minutes.

Lyophilisation

The resulting paste was filled into lyophilisation syringes at 5.5 gportions and the syringes were placed in the lyophiliser. Prior tofreezing, a vacuum of app. 450,000 mtorr (about 600 mbar) was applied tothe samples. Thereafter, the samples were frozen to below −40° C. anddried in the lyophiliser until dry.

Reconstitution

The dried pastes were reconstituted by addition of 7.0 ml of a 2.5%NaHCO₃ solution to each syringe. Specifically, the reconstitution liquidwas added by connecting the syringe containing the dried paste withanother syringe containing the reconstitution solution and opening avalve allowing for communication between the two syringes. Due to thereduced pressure within the syringe containing the dried paste, thereconstitution liquid is automatically drawn into the syringe containingthe dried paste.

Texture Analysis

The consistency of the reconstituted pastes was tested using a textureanalyser (TA.XT.plus, Stable micro systems).

TA Settings

Test mode compression Pre-test speed 5.00 mm/sec Test speed 0.5 mm/secPost-test speed 10 mm/sec Distance 30.0 mm Trigger type Auto Triggerforce 4.0 g Probe P/0.5R ½″ Dia Cylinder

Results

The contents of the compositions in wet and dry state were as follows:

1% Tartaric Acid

Content wet Content dry Content wet Content dry Excipient [g] [g] [W/W%] [W/W %] Gelatine 50.00 50.00 18.33 67.81 Mannitol 20.00 20.00 7.3327.12 BAC 0.01 0.01 0.00 0.01 Tartaric acid 2.73 2.73 1.00 3.70 H₂0200.00 1.00 73.33 1.36 SUM 272.74 73.74 100.00 100.00

The consistency was calculated as area under the resulting curve and theaverage consistency and reconstitution time are shown in the belowtable.

Average consistency Average reconstitution [g*sec] +/− standard time[sec] +/− standard deviation deviation +tartaric acid (N = 6) 1864 +/−579 16 +/− 3

The samples reconstituted spontaneously without any mechanical mixingrequired.

The consistency of the reconstituted paste achieved by having an acidincorporated into the paste prior to drying and reconstituting with abase was similar to the consistency achieved by having a baseincorporated into the paste prior to drying and reconstituting with anacid (see Examples 6 and 7 herein).

Conclusion

A soft smooth consistency was achieved upon reconstitution. Uponreconstitution, the tartaric acid in the dry compositions reacts withthe NaHCO₃ in the reconstitution liquid and CO₂ forms. The CO₂ expandsinside the paste, thereby altering the consistency of the paste.

1. A method for preparing a dry composition comprising the steps of: a)mixing a biocompatible polymer in powder form, an aqueous medium and analkaline compound to obtain a paste, and b) drying the paste, whereinthe alkaline compound is capable of reacting with an acidic compound inan aqueous medium to release a gas.
 2. A method for preparing a drycomposition comprising the steps of: a) mixing a biocompatible polymerin powder form, an aqueous medium and an acidic compound to obtain apaste, and b) drying the paste, wherein the acidic compound is capableof reacting with an alkaline compound in an aqueous medium to release agas.
 3. The method according to any of the preceding claims, wherein thepaste obtained in step a) is subjected to i) a reduced pressure, therebyexpanding the paste, and ii) the expanded paste is frozen, prior to stepb).
 4. The method according to any of the preceding claims wherein thepaste of step a) is further mixed with one or more hydrophiliccompounds.
 5. The method according to any of the preceding claims,wherein the biocompatible polymer consists of powder particles which aresubstantially insoluble in an aqueous medium.
 6. The method according toany of the preceding claims, wherein the biocompatible polymer iscross-linked.
 7. The method according to any of the preceding claims,wherein the biocompatible polymer comprises or consists of gelatine. 8.The method according to claim 7, wherein the gelatine is obtained from amicronized gelatine sponge which has been cross-linked by dry heattreatment.
 9. The method according to any of the preceding claims,wherein the alkaline compound and the acidic compound arephysiologically acceptable compounds.
 10. The method according to any ofthe preceding claims, wherein the gas is CO₂.
 11. The method accordingto any of the preceding claims, wherein the alkaline compound is acarbonate salt, such as a carbonate salt selected from the groupconsisting of sodium bicarbonate (NaHCO₃), sodium carbonate (Na₂CO₃),potassium bicarbonate (KHCO₃), potassium carbonate (K₂CO₃), calciumbicarbonate (Ca(HCO₃)₂), calcium carbonate (CaCO₃), magnesium carbonate(MgCO₃), magnesium bicarbonate (Mg(HCO₃)₂), ammonium bicarbonate(NH₄HCO₃), ammonium carbonate ((NH₄)₂CO₃), gadolinium bicarbonate(Gd(HCO₃)₃, gadolinium carbonate (Gd₂(CO₃)₃), lithium bicarbonate(LiHCO₃), lithium carbonate (LiCO₃), rubidium bicarbonate (RbHCO₃),rubidium carbonate (Rb₂CO₃), zinc carbonate (ZnCO₃), zinc bicarbonate(Zn(HCO₃)₂, iron (II) carbonate (FeCO₃), iron (II) bicarbonate(Fe(HCO₃)₂), silver carbonate (Ag₂CO₃), silver bicarbonate (AgHCO₃),gold (III) carbonate Au₂(CO₃)₃, gold (I) carbonate (Au₂CO₃) and mixturesthereof.
 12. The method according to claim 11, wherein the carbonatesalt is sodium bicarbonate (NaHCO₃).
 13. The method according to any ofthe preceding claims, wherein the acidic compound is selected from thegroup consisting of acetic acid, citric acid, oxalic acid and tartaricacid.
 14. The method according to any of the preceding claims, whereinthe dry composition comprises from about 0.1% to about 10% of thealkaline compound or the acidic compound, for example from about 0.5% toabout 8% of the alkaline compound or the acidic compound, such as fromabout 1% to about 6% of the alkaline compound or the acidic compound orfrom about 1% to about 5% of the alkaline compound or the acidiccompound.
 15. The method according to any of claims 4 to 14, wherein thedry composition comprises from about 10% to about 60% of one or morehydrophilic compounds, for example from about 15% to about 50% of one ormore hydrophilic compounds, such as from about 20% to about 45% of oneor more hydrophilic compounds, for example from about 25% to about 45%of one or more hydrophilic compounds.
 16. The method according to any ofclaims 4 to 15, wherein the one or more hydrophilic compounds is one ormore polyols.
 17. The method according to claim 16, wherein the one ormore polyols is selected from sugar alcohols, sugars and/or derivativesthereof.
 18. The method according to claim 17, wherein the one or morepolyols is a sugar alcohol.
 19. The method according to claim 18,wherein the sugar alcohol is selected from the group consisting ofglycol, glycerol, erythritol, threitol, arabitol, xylitol, ribitol,mannitol, sorbitol, dulcitol, fucitol, iditol, inositol, volemitol,isomalt, maltitol, lactitol, polyglycitol and mixtures thereof.
 20. Themethod according to claim 19, wherein the sugar alcohol is mannitol. 21.The method according to any of claims 4 to 15, wherein the one or morehydrophilic compounds is polyethylene glycol (PEG).
 22. The methodaccording to any of the preceding claims, wherein the drying isfreeze-drying.
 23. The method according to any of the preceding claims,wherein the drying results in a dry composition comprising less thanabout 5% water, preferably less than about 2% water, such as less thanabout 1% water.
 24. The method according to any of the preceding claims,wherein the dry composition further comprises one or more bioactiveagents capable of stimulating haemostasis, wound healing, bone healing,tissue healing and/or tendon healing.
 25. The method according to claim24, wherein the bioactive agent is thrombin.
 26. The method according toany of the preceding claims, wherein the dry composition furthercomprises an extrusion enhancer, such as albumin, preferably human serumalbumin.
 27. The method according to any of the preceding claims,wherein the paste obtained in step a) is transferred into a containersuitable for drying of the paste.
 28. The method according to claim 27,wherein the container is a medical delivery device suitable forreconstituting a dry composition and dispensing a paste.
 29. The methodaccording to any of claims 27 to 28, wherein the container is a syringe.30. The method according to any of the preceding claims, wherein the drycomposition is in the form of a sheet.
 31. The method according to anyof the preceding claims, further comprising a step of adding i) anacidic compound in dry form after step b) if the dry compositioncomprises an alkaline compound, or ii) an alkaline compound in dry formafter step b) if the dry composition comprises an acidic compound,thereby obtaining a dry composition comprising an alkaline compound andan acidic compound.
 32. A method for reconstituting the dry compositionobtained by the method of any of the preceding claims, furthercomprising a step of adding an aqueous medium to the dry composition,wherein the aqueous medium comprises: i) an acidic compound if the drycomposition comprises an alkaline compound, ii) an alkaline compound ifthe dry composition comprises an acidic compound, or iii) neither anacidic nor an alkaline compound if the dry composition comprises both analkaline and an acidic compound according to the method of claim 31,wherein the acidic compound and the alkaline compound react to release agas in the presence of said aqueous medium.
 33. The method according toclaim 32, wherein the dry composition reconstitutes to a paste uponaddition of the aqueous medium without mechanical mixing.
 34. A pasteobtainable by the method of any of claims 32 to
 33. 35. A drycomposition comprising a biocompatible polymer and i) an alkalinecompound, and/or ii) an acidic compound, wherein the alkaline compoundof i) is capable of reacting with an acidic compound in the presence ofan aqueous medium to release a gas and/or wherein the acidic compound ofii) is capable of reacting with an alkaline compound in the presence ofan aqueous medium to release a gas.
 36. A dry composition obtainable bythe method of any of claims 1 to
 31. 37. The dry composition accordingto any of claims 35 to 36 for use in promoting haemostasis and/or woundhealing.
 38. A container comprising: a) a product chamber comprising i)the dry composition according to any of claims 35 to 36 or ii) the drycomposition obtained by the method of any of claims 1 to 31, and b) avalve.
 39. The container according to claim 38 being a medical deliverydevice, preferably a syringe, such as a single-use plastic syringe. 40.A method for reconstituting a dry composition comprising the steps of:a) providing the container of any of claims 38 to 39, said containerbeing the first container, b) providing a second container comprising anaqueous medium, c) connecting the first container and the secondcontainer using suitable connecting means, and d) opening the valve. 41.The method according to claim 40, wherein the aqueous medium comprisesi) an acidic compound if the dry composition comprises an alkalinecompound, ii) an alkaline compound if the dry composition comprises anacidic compound, or iii) neither an acidic nor an alkaline compound ifthe dry composition comprises both an alkaline and an acidic compound.42. A haemostatic kit comprising: a) a first container comprising thedry composition obtained by the method of any of claims 1 to 31 or thecontainer according to any of claims 38 to 39, b) a second containercomprising an aqueous medium as defined in claim 41, and c) optionallyan outer packaging.
 43. A paste suitable for use in haemostasiscomprising a biocompatible polymer, wherein said paste has a consistencyof less than 5000 g×sec.
 44. The paste according to claim 43, whereinsaid biocompatible polymer is in the form of substantiallywater-insoluble particles.
 45. The paste according to any of claims 43to 44, wherein said biocompatible polymer is cross-linked.
 46. The pasteaccording to any of claims 43 to 45, wherein said biocompatible polymercomprises or consists of gelatine.
 47. The paste according to any ofclaims 43 to 46, wherein the consistency of the paste is less than 4500g×sec, such as less than 4000 g×sec, for example less than 3500 g×sec,such as less than 3000 g×sec, for example less than 2500 g×sec, such asless than 2000 g×sec.
 48. The paste according to any of claims 43 to 47,wherein the paste further comprises one or more hydrophilic compounds,such as a sugar alcohol.
 49. The paste according to any of claims 43 to48, wherein the paste further comprises mannitol.
 50. The pasteaccording to any of claims 43 to 49, wherein said paste furthercomprises one or more additional compounds and/or bioactive agentsand/or extrusion enhancers.
 51. The paste according to any of claims 43to 50, wherein said paste comprises thrombin.
 52. The paste according toany of claims 43 to 51, wherein said paste comprises a) a biocompatiblepolymer at about 10% (w/w) to about 40% (w/w), b) an aqueous medium suchas water.
 53. The paste according to any of claims 43 to 52, whereinsaid paste comprises a hydrophilic compound at about 1% (w/w) to about20% (w/w).
 54. The paste according to any of claims 43 to 53, whereinsaid paste comprises a bioactive agent, such as thrombin.
 55. The pasteaccording to any of claims 43 to 54, wherein said paste comprises anextrusion enhancer.
 56. The paste according to any of claims 43 to 55for use in promoting haemostasis and/or wound healing.
 57. A syringecomprising the paste according to any of claims 43 to 55.